- Scan-ID:
- 6288f88d-ff97-4bdc-bee0-abaaa546c4f4Beendet
- Eingereichte URL:
- https://react.dev/learn
- Bericht beendet:
Links · 21 gefunden
Die von der Seite ausgehenden identifizierten Links
| Link | Text |
|---|---|
| https://github.com/facebook/react/releases | Open on GitHub |
| https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export | MDN |
| https://javascript.info/import-export | javascript.info |
| https://transform.tools/html-to-jsx | online converter. |
| https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/class | class |
| https://developer.mozilla.org/en-US/docs/Web/HTML/Element/link | <link> |
| https://javascript.info/operators#string-concatenation-with-binary | string concatenation |
| https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else | if |
| https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator | conditional? operator. |
| https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_AND#short-circuit_evaluation | logical&& syntax |
JavaScript-Variablen · 26 gefunden
Globale JavaScript-Variablen, die in das Window Object einer Seite geladen werden, sind Variablen, die außerhalb von Funktionen deklariert werden und von jeder Stelle des Codes innerhalb des aktuellen Bereichs zugänglich sind
| Name | Typ |
|---|---|
| 0 | object |
| 1 | object |
| 2 | object |
| 3 | object |
| 4 | object |
| onbeforetoggle | object |
| documentPictureInPicture | object |
| onscrollend | object |
| gtag | function |
| dataLayer | object |
Konsolenprotokoll-Meldungen · 0 gefunden
In der Web-Konsole protokollierte Meldungen
HTML
Der HTML-Rohtext der Seite
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class="w-full pt-6 scrolling-touch lg:h-auto grow pe-0 lg:pe-5 lg:pb-16 md:pt-4 lg:pt-4 scrolling-gpu"><!--$--><ul><h3 class="mb-1 text-sm font-bold ms-5 text-tertiary dark:text-tertiary-dark">GET STARTED</h3><li><a title="Quick Start" target="" aria-current="page" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between ps-5 text-base font-bold text-base text-link dark:text-link-dark bg-highlight dark:bg-highlight-dark border-blue-40 hover:bg-highlight hover:text-link dark:hover:bg-highlight-dark dark:hover:text-link-dark" href="/learn"><div>Quick Start<!-- --> </div><span class="pe-1 text-link dark:text-link-dark"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" class="duration-100 ease-in transition rotate-0" style="min-width:20px;min-height:20px"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg></span></a><div class="opacity-100" style="transition:opacity 250ms ease-in-out"><div id="react-collapsed-panel-:R8im6:" aria-hidden="false" role="region" style="box-sizing:border-box"><ul><li><a title="Tutorial: Tic-Tac-Toe" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/tutorial-tic-tac-toe"><div>Tutorial: Tic-Tac-Toe<!-- --> </div></a></li><li><a title="Thinking in React" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/thinking-in-react"><div>Thinking in React<!-- --> </div></a></li></ul></div></div></li><li><a title="Installation" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between ps-5 text-base font-bold text-primary dark:text-primary-dark" href="/learn/installation"><div>Installation<!-- --> </div><span class="pe-1 text-tertiary dark:text-tertiary-dark"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" class="duration-100 ease-in transition -rotate-90 rtl:rotate-90" 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class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/start-a-new-react-project"><div>Start a New React Project<!-- --> </div></a></li><li><a title="Add React to an Existing Project" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/add-react-to-an-existing-project"><div>Add React to an Existing Project<!-- --> </div></a></li><li><a title="Editor Setup" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/editor-setup"><div>Editor Setup<!-- --> </div></a></li><li><a title="Using TypeScript" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/typescript"><div>Using TypeScript<!-- --> </div></a></li><li><a title="React Developer Tools" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/react-developer-tools"><div>React Developer Tools<!-- --> </div></a></li><li><a title="React Compiler" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/react-compiler"><div>React Compiler<!-- --> 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13.8537479,17.0822749 13.7952635,17.2147751 C13.7368889,17.3472613 13.6248314,17.4504531 13.4856467,17.5000531 C12.6833967,17.7332867 11.0855382,17.9999981 7.99965585,17.9999981 Z" id="Shape"></path></g></g></svg></div></a></li></ul></div></div></li><li role="separator" class="mt-4 mb-2 ms-5 border-b border-border dark:border-border-dark"></li><h3 class="mb-1 text-sm font-bold ms-5 text-tertiary dark:text-tertiary-dark mt-2">LEARN REACT</h3><li><a title="Describing the UI" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between ps-5 text-base font-bold text-primary dark:text-primary-dark" href="/learn/describing-the-ui"><div>Describing the UI<!-- --> </div><span class="pe-1 text-tertiary dark:text-tertiary-dark"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" class="duration-100 ease-in transition -rotate-90 rtl:rotate-90" style="min-width:20px;min-height:20px"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg></span></a><div class="opacity-50" style="transition:opacity 250ms ease-in-out"><div id="react-collapsed-panel-:R9am6:" aria-hidden="true" role="region" style="box-sizing:border-box;display:none;height:0px;overflow:hidden"><ul><li><a title="Your First Component" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/your-first-component"><div>Your First Component<!-- --> </div></a></li><li><a title="Importing and Exporting Components" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/importing-and-exporting-components"><div>Importing and Exporting Components<!-- --> </div></a></li><li><a title="Writing Markup with JSX" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/writing-markup-with-jsx"><div>Writing Markup with JSX<!-- --> </div></a></li><li><a title="JavaScript in JSX with Curly Braces" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/javascript-in-jsx-with-curly-braces"><div>JavaScript in JSX with Curly Braces<!-- --> </div></a></li><li><a title="Passing Props to a Component" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/passing-props-to-a-component"><div>Passing Props to a Component<!-- --> </div></a></li><li><a title="Conditional Rendering" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/conditional-rendering"><div>Conditional Rendering<!-- --> </div></a></li><li><a title="Rendering Lists" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/rendering-lists"><div>Rendering Lists<!-- --> </div></a></li><li><a title="Keeping Components Pure" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/keeping-components-pure"><div>Keeping Components Pure<!-- --> </div></a></li><li><a title="Your UI as a Tree" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/understanding-your-ui-as-a-tree"><div>Your UI as a Tree<!-- --> </div></a></li></ul></div></div></li><li><a title="Adding Interactivity" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between ps-5 text-base font-bold text-primary dark:text-primary-dark" href="/learn/adding-interactivity"><div>Adding Interactivity<!-- --> </div><span class="pe-1 text-tertiary dark:text-tertiary-dark"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" class="duration-100 ease-in transition -rotate-90 rtl:rotate-90" style="min-width:20px;min-height:20px"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg></span></a><div class="opacity-50" style="transition:opacity 250ms ease-in-out"><div id="react-collapsed-panel-:R9im6:" aria-hidden="true" role="region" style="box-sizing:border-box;display:none;height:0px;overflow:hidden"><ul><li><a title="Responding to Events" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/responding-to-events"><div>Responding to Events<!-- --> </div></a></li><li><a title="State: A Component's Memory" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/state-a-components-memory"><div>State: A Component's Memory<!-- --> </div></a></li><li><a title="Render and Commit" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/render-and-commit"><div>Render and Commit<!-- --> </div></a></li><li><a title="State as a Snapshot" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/state-as-a-snapshot"><div>State as a Snapshot<!-- --> </div></a></li><li><a title="Queueing a Series of State Updates" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/queueing-a-series-of-state-updates"><div>Queueing a Series of State Updates<!-- --> </div></a></li><li><a title="Updating Objects in State" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/updating-objects-in-state"><div>Updating Objects in State<!-- --> </div></a></li><li><a title="Updating Arrays in State" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/updating-arrays-in-state"><div>Updating Arrays in State<!-- --> </div></a></li></ul></div></div></li><li><a title="Managing State" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between ps-5 text-base font-bold text-primary dark:text-primary-dark" href="/learn/managing-state"><div>Managing State<!-- --> </div><span class="pe-1 text-tertiary dark:text-tertiary-dark"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" class="duration-100 ease-in transition -rotate-90 rtl:rotate-90" style="min-width:20px;min-height:20px"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg></span></a><div class="opacity-50" style="transition:opacity 250ms ease-in-out"><div id="react-collapsed-panel-:R9qm6:" aria-hidden="true" role="region" style="box-sizing:border-box;display:none;height:0px;overflow:hidden"><ul><li><a title="Reacting to Input with State" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/reacting-to-input-with-state"><div>Reacting to Input with State<!-- --> </div></a></li><li><a title="Choosing the State Structure" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/choosing-the-state-structure"><div>Choosing the State Structure<!-- --> </div></a></li><li><a title="Sharing State Between Components" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/sharing-state-between-components"><div>Sharing State Between Components<!-- --> </div></a></li><li><a title="Preserving and Resetting State" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/preserving-and-resetting-state"><div>Preserving and Resetting State<!-- --> </div></a></li><li><a title="Extracting State Logic into a Reducer" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/extracting-state-logic-into-a-reducer"><div>Extracting State Logic into a Reducer<!-- --> </div></a></li><li><a title="Passing Data Deeply with Context" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/passing-data-deeply-with-context"><div>Passing Data Deeply with Context<!-- --> </div></a></li><li><a title="Scaling Up with Reducer and Context" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/scaling-up-with-reducer-and-context"><div>Scaling Up with Reducer and Context<!-- --> </div></a></li></ul></div></div></li><li><a title="Escape Hatches" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between ps-5 text-base font-bold text-primary dark:text-primary-dark" href="/learn/escape-hatches"><div>Escape Hatches<!-- --> </div><span class="pe-1 text-tertiary dark:text-tertiary-dark"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20" class="duration-100 ease-in transition -rotate-90 rtl:rotate-90" style="min-width:20px;min-height:20px"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg></span></a><div class="opacity-50" style="transition:opacity 250ms ease-in-out"><div id="react-collapsed-panel-:Ra2m6:" aria-hidden="true" role="region" style="box-sizing:border-box;display:none;height:0px;overflow:hidden"><ul><li><a title="Referencing Values with Refs" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/referencing-values-with-refs"><div>Referencing Values with Refs<!-- --> </div></a></li><li><a title="Manipulating the DOM with Refs" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/manipulating-the-dom-with-refs"><div>Manipulating the DOM with Refs<!-- --> </div></a></li><li><a title="Synchronizing with Effects" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/synchronizing-with-effects"><div>Synchronizing with Effects<!-- --> </div></a></li><li><a title="You Might Not Need an Effect" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/you-might-not-need-an-effect"><div>You Might Not Need an Effect<!-- --> </div></a></li><li><a title="Lifecycle of Reactive Effects" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/lifecycle-of-reactive-effects"><div>Lifecycle of Reactive Effects<!-- --> </div></a></li><li><a title="Separating Events from Effects" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/separating-events-from-effects"><div>Separating Events from Effects<!-- --> </div></a></li><li><a title="Removing Effect Dependencies" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/removing-effect-dependencies"><div>Removing Effect Dependencies<!-- --> </div></a></li><li><a title="Reusing Logic with Custom Hooks" target="" class="p-2 pe-2 w-full rounded-none lg:rounded-e-2xl text-start hover:bg-gray-5 dark:hover:bg-gray-80 relative flex items-center justify-between text-sm ps-6 ps-5 text-base text-secondary dark:text-secondary-dark" href="/learn/reusing-logic-with-custom-hooks"><div>Reusing Logic with Custom Hooks<!-- --> </div></a></li></ul></div></div></li></ul><!--/$--><div class="h-20"></div></nav><div class="fixed bottom-0 hidden lg:block"><div class="max-w-custom-xs w-80 lg:w-auto py-3 shadow-lg rounded-lg m-4 bg-wash dark:bg-gray-95 px-4 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5.1415C14.3158 4.23242 13.9609 3.36058 13.3292 2.71777C12.6975 2.07496 11.8407 1.71383 10.9474 1.71383L4.21053 1.71383C3.5405 1.71383 2.89793 1.98468 2.42415 2.46679C1.95038 2.94889 1.68421 3.60277 1.68421 4.28458L1.68421 7.71225C1.68421 8.16679 1.86166 8.60271 2.1775 8.92411C2.49335 9.24552 2.92174 9.42608 3.36842 9.42608L8 9.42608C8.28237 9.42608 8.54595 9.5701 8.70195 9.80961C8.85794 10.0491 8.88558 10.3523 8.77555 10.6169L7.11114 14.6201C7 14.8875 6.98105 15.1852 7.05738 15.4649C7.1337 15.7446 7.30079 15.9897 7.53147 16.1605L7.62458 16.2294Z" fill="currentColor"></path></svg></button></div></div></aside></div></div></div></div><!--$--><main class="min-w-0 isolate"><article class="font-normal break-words text-primary dark:text-primary-dark"><div class="ps-0"><div class=""><div class="px-5 sm:px-12 pt-3.5"><div class="max-w-4xl ms-0 2xl:mx-auto"><div class="flex flex-wrap"><div class="flex mb-3 mt-0.5 items-center"><a class="text-link dark:text-link-dark text-sm tracking-wide font-bold uppercase me-1 hover:underline" href="/learn">Learn React</a><span class="inline-block me-1 text-link dark:text-link-dark text-lg rtl:rotate-180"><svg width="20" height="20" viewBox="0 0 20 20" fill="none" xmlns="http://www.w3.org/2000/svg"><path d="M6.86612 13.6161C6.37796 14.1043 6.37796 14.8957 6.86612 15.3839C7.35427 15.872 8.14572 15.872 8.63388 15.3839L13.1339 10.8839C13.622 10.3957 13.622 9.60428 13.1339 9.11612L8.63388 4.61612C8.14572 4.12797 7.35427 4.12797 6.86612 4.61612C6.37796 5.10428 6.37796 5.89573 6.86612 6.38388L10.4822 10L6.86612 13.6161Z" fill="currentColor"></path></svg></span></div></div><h1 class="mdx-heading mt-0 text-primary dark:text-primary-dark -mx-.5 break-words text-5xl font-display font-bold leading-tight">Quick Start<a href="#undefined" aria-label="Link for this heading" title="Link for this heading" class="mdx-header-anchor hidden"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h1></div></div></div><div class="px-5 sm:px-12"><div class="max-w-7xl mx-auto"><div class="max-w-4xl ms-0 2xl:mx-auto"><div class="font-display text-xl text-primary dark:text-primary-dark leading-relaxed"><p class="whitespace-pre-wrap my-4">Welcome to the React documentation! This page will give you an introduction to the 80% of React concepts that you will use on a daily basis.</p></div>
<div class="p-6 xl:p-8 pb-4 xl:pb-6 bg-card dark:bg-card-dark rounded-2xl shadow-inner-border dark:shadow-inner-border-dark text-base text-secondary dark:text-secondary-dark my-8"><h3 class="mdx-heading text-primary dark:text-primary-dark mt-0 mb-3 leading-tight text-2xl font-display leading-9 text-primary dark:text-primary-dark font-bold my-6">You will learn</h3><ul class="ms-6 my-3 list-disc">
<li class="leading-relaxed mb-1">How to create and nest components</li>
<li class="leading-relaxed mb-1">How to add markup and styles</li>
<li class="leading-relaxed mb-1">How to display data</li>
<li class="leading-relaxed mb-1">How to render conditions and lists</li>
<li class="leading-relaxed mb-1">How to respond to events and update the screen</li>
<li class="leading-relaxed mb-1">How to share data between components</li>
</ul></div>
<h2 id="components" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Creating and nesting components <a href="#components" aria-label="Link for Creating and nesting components " title="Link for Creating and nesting components " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">React apps are made out of <em>components</em>. A component is a piece of the UI (user interface) that has its own logic and appearance. A component can be as small as a button, or as large as an entire page.</p>
<p class="whitespace-pre-wrap my-4">React components are JavaScript functions that return markup:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span>I'm a button<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Now that you’ve declared <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code>, you can nest it into another component:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyApp</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>Welcome to my app<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Notice that <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><MyButton /></code> starts with a capital letter. That’s how you know it’s a React component. React component names must always start with a capital letter, while HTML tags must be lowercase.</p>
<p class="whitespace-pre-wrap my-4">Have a look at the result:</p>
</div><!--$--><div class="sandpack sandpack--playground w-full my-8" dir="ltr"><div class="sp-wrapper"><div class="shadow-lg dark:shadow-lg-dark rounded-lg" style="contain:content"><div class="bg-wash dark:bg-card-dark flex justify-between items-center relative z-10 border-b border-border dark:border-border-dark rounded-t-lg text-lg"><div class="flex-1 grow min-w-0 px-4 lg:px-6"><div><div class="relative overflow-hidden"><div class="w-[fit-content] invisible"><div class=" sp-tabs" translate="no"><div aria-label="Select active file" class=" sp-tabs-scrollable-container" role="tablist"><button aria-selected="true" class=" sp-tab-button" data-active="true" role="tab" title="/src/App.js" type="button">App.js</button></div></div></div><button class="absolute top-0 start-[2px]" id="headlessui-listbox-button-:R9iicq6:" aria-haspopup="true" aria-expanded="false" data-headlessui-state="" type="button"><span class="h-full py-2 px-1 mt-px -mb-px flex border-b text-link dark:text-link-dark border-link dark:border-link-dark items-center text-md leading-tight truncate" style="max-width:160px">App.js</span></button></div></div></div><div class="px-3 flex items-center justify-end text-start" translate="yes"><button class="text-sm text-primary dark:text-primary-dark inline-flex items-center hover:text-link duration-100 ease-in transition mx-1" title="Download Sandbox" type="button"><svg width="1em" height="1em" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" class="inline me-1"><path d="M20.5 22H3.5C3.10218 22 2.72064 21.842 2.43934 21.5607C2.15804 21.2794 2 20.8978 2 20.5V15.5C2 15.3674 2.05268 15.2402 2.14645 15.1464C2.24021 15.0527 2.36739 15 2.5 15H3.5C3.63261 15 3.75979 15.0527 3.85355 15.1464C3.94732 15.2402 4 15.3674 4 15.5V20H20V15.5C20 15.3674 20.0527 15.2402 20.1464 15.1464C20.2402 15.0527 20.3674 15 20.5 15H21.5C21.6326 15 21.7598 15.0527 21.8536 15.1464C21.9473 15.2402 22 15.3674 22 15.5V20.5C22 20.8978 21.842 21.2794 21.5607 21.5607C21.2794 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value="N4IgZglgNgpgziAXKOAnAxgeggOwCYwAeAdAFYLIjoD2OALjPUiBALYAO1qdABAEowAhujoAaHsB4BlOqggiAstQI8AvjzCpqrHgB0QqISP0BuXTjaduEnukOCGfatV7rN2vQaN0AtHm2Y6FAQjHSm5pZcvPrEmHB0AJ6wcMTocHDhOBEcUTwAguzsGlo6MZgF7JnmNDjxPFouPAC8tvaOznQAFP7oAK6socQA5jB0AKKwA_QAQgkAknid-g1hIACUa2Y4K8SG-DCoSzg8PAA8MnKKyjAAfOYnJ6cVPJh3x2eYF_J0SgRvmyBRCw4NNcIJUAkkGBBFA4DBVED2MIANaCEZkOC0JCgGoMJiIEDAe6eHCCAb6RCeewiYgEABu-lExP0dIOcAgtApngADMRedzGcyQKxBLgufo4hhsPsSORBe99HA7BB2HQMkgJMSToq6ODVpTlt4fEq5Kq4Dx4nr5Q9PAAjXrQPDirzCXwmlVqnj2x3Wh76BjxZ3Ut3Ks08AO8Hw-Rh0prkfysX3akAwUgwYwaw2u42hz2p9OrYkIoUEdiMAg4dAhdWUonvZPB50APQAjAAOPl8pNUo0J5vtzsCwFanvZ91m5sAVkH-iLTIVIHpABEYGX9pXq1zgKpzKpAcDQaSIVCYXCESB2L1bcEsLgCCQABZ0VhQbFUWh4ujMU4AQiXAHkAGEABUAE0AAUxh4J8XzeU4YKgHgoEEHAhiafRGH0OCHyEPA3keAZdVsB9wThOh0JAABVYCADEfDbLDiVOQjBB4UkBgoukQgAdysVZbA_UIKO4iA8DoB8mnpeQYB8ESxIfcRcAgOgIBhHMYRgJoWy7EB8LOFS6FgG4l2oPopjoU5MAMozzEsnDBDw2zbWUBI9NOPAIDpHhRIolYsMsjy6TgzBnLwVzbMwBCbn3CAQTBY9EGhWF4SBNAsAqDE31xUJmDAXpKxU2geAUBJpl6Og6FoTo1k1d5DDoXpUGOI4bVOe0KtoPSbTmAByHRWPayqsnrD5Bs64lNl3cxzCIPieAIaFeigXg8oKjljhKipqtqk56sa5qR3czyuoeeCWxuAB1GAoBoAZw2oHhWASHhBEKOzzpHR4SrKjrjleQ7MECvTJpwHccBiuKj0hRLTxSkA0riRJklSdIssE_EQAAKh2r1qEIY0IAAL1wIZKWc1ACFQHxnMILYwfMULnrrE4wA_HxoVYaAEkpOAULgY0DggMAthOEVUCGXBKQAJm5dhaeJJE8A81DKW5OnppwB8WxxsWJZwHxKvYVWRY0Nn2UJmBpaluX1eGh8pZ18E9YN6gjZ4NXiVZ-gCYt6XZfl0GNYfABmR3xdwF23Y994vbdInLZ4dsbamu2ABYw-dw3jc9s348pFsADZk8Du3JwziOs_dk3Y59hOW1T4v6c1gvy_1yvo5Z3PfcT62A6bmgVGZ03vfNuviClmBWFt8wlpxxXlaGHxcGCHAZMtbg_cbjWIcPcFoaSs9zwYDhkIYZg7CEBgfGDHxXvYEBVCAA" name="parameters"><input type="hidden" value="file=%2Fsrc%2FApp.js&utm_medium=sandpack" name="query"></form><svg width="1em" height="1em" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" class="inline mx-1 relative top-[1px]"><path d="M20.5001 2H15.5001C15.3675 2 15.2403 2.05268 15.1465 2.14645C15.0528 2.24021 15.0001 2.36739 15.0001 2.5V3.5C15.0001 3.63261 15.0528 3.75979 15.1465 3.85355C15.2403 3.94732 15.3675 4 15.5001 4H18.5901L7.6501 14.94C7.60323 14.9865 7.56604 15.0418 7.54065 15.1027C7.51527 15.1636 7.5022 15.229 7.5022 15.295C7.5022 15.361 7.51527 15.4264 7.54065 15.4873C7.56604 15.5482 7.60323 15.6035 7.6501 15.65L8.3501 16.35C8.39658 16.3969 8.45188 16.4341 8.51281 16.4594C8.57374 16.4848 8.63909 16.4979 8.7051 16.4979C8.7711 16.4979 8.83646 16.4848 8.89738 16.4594C8.95831 16.4341 9.01362 16.3969 9.0601 16.35L20.0001 5.41V8.5C20.0001 8.63261 20.0528 8.75979 20.1465 8.85355C20.2403 8.94732 20.3675 9 20.5001 9H21.5001C21.6327 9 21.7599 8.94732 21.8537 8.85355C21.9474 8.75979 22.0001 8.63261 22.0001 8.5V3.5C22.0001 3.10218 21.8421 2.72064 21.5608 2.43934C21.2795 2.15804 20.8979 2 20.5001 2V2Z" fill="currentColor"></path><path d="M21.5 13H20.5C20.3674 13 20.2402 13.0527 20.1464 13.1464C20.0527 13.2402 20 13.3674 20 13.5V20H4V4H10.5C10.6326 4 10.7598 3.94732 10.8536 3.85355C10.9473 3.75979 11 3.63261 11 3.5V2.5C11 2.36739 10.9473 2.24021 10.8536 2.14645C10.7598 2.05268 10.6326 2 10.5 2H3.5C3.10218 2 2.72064 2.15804 2.43934 2.43934C2.15804 2.72064 2 3.10218 2 3.5V20.5C2 20.8978 2.15804 21.2794 2.43934 21.5607C2.72064 21.842 3.10218 22 3.5 22H20.5C20.8978 22 21.2794 21.842 21.5607 21.5607C21.842 21.2794 22 20.8978 22 20.5V13.5C22 13.3674 21.9473 13.2402 21.8536 13.1464C21.7598 13.0527 21.6326 13 21.5 13Z" fill="currentColor"></path></svg><span class="hidden md:block">Fork</span></button></div></div><div class=" sp-layout"><div class=" sp-editor sp-stack"><div class=" sp-code-editor"><div aria-autocomplete="list" aria-label="Code Editor for App.js" aria-multiline="true" class="sp-pristine sp-javascript sp-cm" role="textbox" tabindex="0" translate="no"><pre class=" sp-pre-placeholder" style="margin-left:var(--sp-space-11)"><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span>
I'm a button
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyApp</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>Welcome to my app<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-punctuation">/></span>
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
</pre></div></div></div><div class=" order-last xl:order-2 sp-stack"><div class="p-0 sm:p-2 md:p-4 lg:p-8 bg-card dark:bg-wash-dark h-full relative md:rounded-b-lg lg:rounded-b-none"><div style="position:relative"><iframe class="rounded-t-none bg-white md:shadow-md sm:rounded-lg w-full max-w-full transition-opacity absolute opacity-0 pointer-events-none duration-75" title="Sandbox Preview" style="height:15px;z-index:-1" sandbox="allow-forms allow-modals allow-popups allow-presentation allow-same-origin allow-scripts allow-downloads allow-pointer-lock" allow="accelerometer; camera; encrypted-media; geolocation; gyroscope; hid; microphone; midi; clipboard-write;" src="https://786946de.sandpack-bundler-4bw.pages.dev"></iframe></div></div></div><button translate="yes" class="sandpack-expand flex text-base justify-between dark:border-card-dark bg-wash dark:bg-card-dark items-center z-10 p-1 w-full order-2 xl:order-last border-b-1 relative top-0"><span class="flex p-2 focus:outline-none text-primary dark:text-primary-dark leading-[20px]"><svg class="rotate-0 inline me-1.5 text-xl" xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg>Show more</span></button></div></div></div></div><!--/$--><div class="max-w-4xl ms-0 2xl:mx-auto">
<p class="whitespace-pre-wrap my-4">The <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">export default</code> keywords specify the main component in the file. If you’re not familiar with some piece of JavaScript syntax, <a href="https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal">MDN</a> and <a href="https://javascript.info/import-export" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal">javascript.info</a> have great references.</p>
<h2 id="writing-markup-with-jsx" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Writing markup with JSX <a href="#writing-markup-with-jsx" aria-label="Link for Writing markup with JSX " title="Link for Writing markup with JSX " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">The markup syntax you’ve seen above is called <em>JSX</em>. It is optional, but most React projects use JSX for its convenience. All of the <a class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal" href="/learn/installation">tools we recommend for local development</a> support JSX out of the box.</p>
<p class="whitespace-pre-wrap my-4">JSX is stricter than HTML. You have to close tags like <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><br /></code>. Your component also can’t return multiple JSX tags. You have to wrap them into a shared parent, like a <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><div>...</div></code> or an empty <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><>...</></code> wrapper:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">AboutPage</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>About<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">p</span><span class="sp-syntax-punctuation">></span>Hello there.<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">br</span> <span class="sp-syntax-punctuation">/></span>How do you do?<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">p</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">If you have a lot of HTML to port to JSX, you can use an <a href="https://transform.tools/html-to-jsx" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal">online converter.</a></p>
<h2 id="adding-styles" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Adding styles <a href="#adding-styles" aria-label="Link for Adding styles " title="Link for Adding styles " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">In React, you specify a CSS class with <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">className</code>. It works the same way as the HTML <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/class" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal"><code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">class</code></a> attribute:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">img</span> <span class="sp-syntax-property">className</span>=<span class="sp-syntax-string">"avatar"</span> <span class="sp-syntax-punctuation">/></span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Then you write the CSS rules for it in a separate CSS file:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-comment">/* In your CSS */</span><br></div><div class="cm-line ">.avatar <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-property">border-radius</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">50</span><span class="sp-syntax-keyword">%</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">React does not prescribe how you add CSS files. In the simplest case, you’ll add a <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/link" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal"><code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><link></code></a> tag to your HTML. If you use a build tool or a framework, consult its documentation to learn how to add a CSS file to your project.</p>
<h2 id="displaying-data" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Displaying data <a href="#displaying-data" aria-label="Link for Displaying data " title="Link for Displaying data " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">JSX lets you put markup into JavaScript. Curly braces let you “escape back” into JavaScript so that you can embed some variable from your code and display it to the user. For example, this will display <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">user.name</code>:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">user</span>.<span class="sp-syntax-property">name</span><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">You can also “escape into JavaScript” from JSX attributes, but you have to use curly braces <em>instead of</em> quotes. For example, <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">className="avatar"</code> passes the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">"avatar"</code> string as the CSS class, but <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">src={user.imageUrl}</code> reads the JavaScript <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">user.imageUrl</code> variable value, and then passes that value as the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">src</code> attribute:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">img</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-property">className</span>=<span class="sp-syntax-string">"avatar"</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-property">src</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">user</span>.<span class="sp-syntax-property">imageUrl</span><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">You can put more complex expressions inside the JSX curly braces too, for example, <a href="https://javascript.info/operators#string-concatenation-with-binary" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal">string concatenation</a>:</p>
</div><!--$--><div class="sandpack sandpack--playground w-full my-8" dir="ltr"><div class="sp-wrapper"><div class="shadow-lg dark:shadow-lg-dark rounded-lg" style="contain:content"><div class="bg-wash dark:bg-card-dark flex justify-between items-center relative z-10 border-b border-border dark:border-border-dark rounded-t-lg text-lg"><div class="flex-1 grow min-w-0 px-4 lg:px-6"><div><div class="relative overflow-hidden"><div class="w-[fit-content] invisible"><div class=" sp-tabs" translate="no"><div aria-label="Select active file" class=" sp-tabs-scrollable-container" role="tablist"><button aria-selected="true" class=" sp-tab-button" data-active="true" role="tab" title="/src/App.js" type="button">App.js</button></div></div></div><button class="absolute top-0 start-[2px]" id="headlessui-listbox-button-:R9ikcq6:" aria-haspopup="true" aria-expanded="false" data-headlessui-state="" type="button"><span class="h-full py-2 px-1 mt-px -mb-px flex border-b text-link dark:text-link-dark border-link dark:border-link-dark items-center text-md leading-tight truncate" style="max-width:160px">App.js</span></button></div></div></div><div class="px-3 flex items-center justify-end text-start" translate="yes"><button class="text-sm text-primary dark:text-primary-dark inline-flex items-center hover:text-link duration-100 ease-in transition mx-1" title="Download Sandbox" type="button"><svg width="1em" height="1em" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" class="inline me-1"><path d="M20.5 22H3.5C3.10218 22 2.72064 21.842 2.43934 21.5607C2.15804 21.2794 2 20.8978 2 20.5V15.5C2 15.3674 2.05268 15.2402 2.14645 15.1464C2.24021 15.0527 2.36739 15 2.5 15H3.5C3.63261 15 3.75979 15.0527 3.85355 15.1464C3.94732 15.2402 4 15.3674 4 15.5V20H20V15.5C20 15.3674 20.0527 15.2402 20.1464 15.1464C20.2402 15.0527 20.3674 15 20.5 15H21.5C21.6326 15 21.7598 15.0527 21.8536 15.1464C21.9473 15.2402 22 15.3674 22 15.5V20.5C22 20.8978 21.842 21.2794 21.5607 21.5607C21.2794 21.842 20.8978 22 20.5 22Z" fill="currentColor"></path><path d="M10.9999 2.5V13.79L8.81994 11.61C8.72479 11.5178 8.59747 11.4662 8.46494 11.4662C8.33241 11.4662 8.20509 11.5178 8.10994 11.61L7.39994 12.32C7.30769 12.4151 7.2561 12.5425 7.2561 12.675C7.2561 12.8075 7.30769 12.9348 7.39994 13.03L10.9399 16.56C11.0785 16.7003 11.2436 16.8117 11.4255 16.8877C11.6075 16.9637 11.8027 17.0029 11.9999 17.0029C12.1971 17.0029 12.3924 16.9637 12.5743 16.8877C12.7563 16.8117 12.9214 16.7003 13.0599 16.56L16.5999 13C16.6922 12.9048 16.7438 12.7775 16.7438 12.645C16.7438 12.5125 16.6922 12.3851 16.5999 12.29L15.8899 11.58C15.7948 11.4878 15.6675 11.4362 15.5349 11.4362C15.4024 11.4362 15.2751 11.4878 15.1799 11.58L12.9999 13.79V2.5C12.9999 2.36739 12.9473 2.24021 12.8535 2.14645C12.7597 2.05268 12.6325 2 12.4999 2H11.4999C11.3673 2 11.2402 2.05268 11.1464 2.14645C11.0526 2.24021 10.9999 2.36739 10.9999 2.5Z" fill="currentColor"></path></svg> Download</button><button class="text-sm text-primary dark:text-primary-dark inline-flex items-center hover:text-link duration-100 ease-in transition mx-1" title="Reset Sandbox" type="button"><svg width="1em" height="1em" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" class="inline mx-1 relative"><path d="M13.8982 5.20844C12.4626 4.88688 10.9686 4.93769 9.55821 5.35604L11.8524 3.06184C11.8989 3.0154 11.9357 2.96028 11.9608 2.89961C11.986 2.83894 11.9989 2.77391 11.9989 2.70824C11.9989 2.64256 11.986 2.57754 11.9608 2.51686C11.9357 2.45619 11.8989 2.40107 11.8524 2.35464L11.1456 1.64784C11.0992 1.60139 11.0441 1.56455 10.9834 1.53942C10.9227 1.51428 10.8577 1.50134 10.792 1.50134C10.7263 1.50134 10.6613 1.51428 10.6006 1.53942C10.54 1.56455 10.4848 1.60139 10.4384 1.64784L6.14571 5.94054C6.00654 6.07969 5.89615 6.2449 5.82083 6.42673C5.74551 6.60855 5.70675 6.80343 5.70675 7.00024C5.70675 7.19704 5.74551 7.39192 5.82083 7.57374C5.89615 7.75557 6.00654 7.92078 6.14571 8.05994L10.4387 12.3529C10.5325 12.4465 10.6595 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for App.js" aria-multiline="true" class="sp-pristine sp-javascript sp-cm" role="textbox" tabindex="0" translate="no"><pre class=" sp-pre-placeholder" style="margin-left:var(--sp-space-11)"><span class="sp-syntax-keyword">const</span> <span class="sp-syntax-plain">user</span> = <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-property">name</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'Hedy Lamarr'</span><span class="sp-syntax-punctuation">,</span>
<span class="sp-syntax-property">imageUrl</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'https://i.imgur.com/yXOvdOSs.jpg'</span><span class="sp-syntax-punctuation">,</span>
<span class="sp-syntax-property">imageSize</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">90</span><span class="sp-syntax-punctuation">,</span>
<span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">Profile</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span><span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">user</span>.<span class="sp-syntax-property">name</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">img</span>
<span class="sp-syntax-property">className</span>=<span class="sp-syntax-string">"avatar"</span>
<span class="sp-syntax-property">src</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">user</span>.<span class="sp-syntax-property">imageUrl</span><span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-property">alt</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-string">'Photo of '</span> + <span class="sp-syntax-plain">user</span>.<span class="sp-syntax-property">name</span><span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-property">style</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-property">width</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-plain">user</span>.<span class="sp-syntax-property">imageSize</span><span class="sp-syntax-punctuation">,</span>
<span class="sp-syntax-property">height</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-plain">user</span>.<span class="sp-syntax-property">imageSize</span>
<span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-punctuation">/></span>
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
</pre></div></div></div><div class=" order-last xl:order-2 sp-stack"><div class="p-0 sm:p-2 md:p-4 lg:p-8 bg-card dark:bg-wash-dark h-full relative md:rounded-b-lg lg:rounded-b-none"><div style="position:relative"><iframe class="rounded-t-none bg-white md:shadow-md sm:rounded-lg w-full max-w-full transition-opacity absolute opacity-0 pointer-events-none duration-75" title="Sandbox Preview" style="height:15px;z-index:-1"></iframe></div></div></div><button translate="yes" class="sandpack-expand flex text-base justify-between dark:border-card-dark bg-wash dark:bg-card-dark items-center z-10 p-1 w-full order-2 xl:order-last border-b-1 relative top-0"><span class="flex p-2 focus:outline-none text-primary dark:text-primary-dark leading-[20px]"><svg class="rotate-0 inline me-1.5 text-xl" xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg>Show more</span></button></div></div></div></div><!--/$--><div class="max-w-4xl ms-0 2xl:mx-auto">
<p class="whitespace-pre-wrap my-4">In the above example, <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">style={{}}</code> is not a special syntax, but a regular <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">{}</code> object inside the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">style={ }</code> JSX curly braces. You can use the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">style</code> attribute when your styles depend on JavaScript variables.</p>
<h2 id="conditional-rendering" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Conditional rendering <a href="#conditional-rendering" aria-label="Link for Conditional rendering " title="Link for Conditional rendering " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">In React, there is no special syntax for writing conditions. Instead, you’ll use the same techniques as you use when writing regular JavaScript code. For example, you can use an <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal"><code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">if</code></a> statement to conditionally include JSX:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">let</span> <span class="sp-syntax-plain">content</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-keyword">if</span> <span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">isLoggedIn</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-plain">content</span> = <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">AdminPanel</span> <span class="sp-syntax-punctuation">/></span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-keyword">else</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-plain">content</span> = <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">LoginForm</span> <span class="sp-syntax-punctuation">/></span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">content</span><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">If you prefer more compact code, you can use the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal">conditional <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">?</code> operator.</a> Unlike <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">if</code>, it works inside JSX:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">isLoggedIn</span> ? <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">AdminPanel</span> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span> : <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">LoginForm</span> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">When you don’t need the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">else</code> branch, you can also use a shorter <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_AND#short-circuit_evaluation" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal">logical <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">&&</code> syntax</a>:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">isLoggedIn</span> && <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">AdminPanel</span> <span class="sp-syntax-punctuation">/></span><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">All of these approaches also work for conditionally specifying attributes. If you’re unfamiliar with some of this JavaScript syntax, you can start by always using <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">if...else</code>.</p>
<h2 id="rendering-lists" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Rendering lists <a href="#rendering-lists" aria-label="Link for Rendering lists " title="Link for Rendering lists " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">You will rely on JavaScript features like <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal"><code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">for</code> loop</a> and the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map" target="_blank" rel="nofollow noopener noreferrer" class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal">array <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">map()</code> function</a> to render lists of components.</p>
<p class="whitespace-pre-wrap my-4">For example, let’s say you have an array of products:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">const</span> <span class="sp-syntax-plain">products</span> = <span class="sp-syntax-punctuation">[</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'Cabbage'</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">1</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">,</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'Garlic'</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">2</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">,</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'Apple'</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">3</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">,</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">]</span><span class="sp-syntax-punctuation">;</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Inside your component, use the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">map()</code> function to transform an array of products into an array of <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><li></code> items:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">const</span> <span class="sp-syntax-plain">listItems</span> = <span class="sp-syntax-plain">products</span>.<span class="sp-syntax-property">map</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">product</span> <span class="sp-syntax-punctuation">=></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">li</span> <span class="sp-syntax-property">key</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">product</span>.<span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">product</span>.<span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">li</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><br></div><div class="cm-line "><span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">ul</span><span class="sp-syntax-punctuation">></span><span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">listItems</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">ul</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Notice how <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><li></code> has a <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">key</code> attribute. For each item in a list, you should pass a string or a number that uniquely identifies that item among its siblings. Usually, a key should be coming from your data, such as a database ID. React uses your keys to know what happened if you later insert, delete, or reorder the items.</p>
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for App.js" aria-multiline="true" class="sp-pristine sp-javascript sp-cm" role="textbox" tabindex="0" translate="no"><pre class=" sp-pre-placeholder" style="margin-left:var(--sp-space-11)"><span class="sp-syntax-keyword">const</span> <span class="sp-syntax-plain">products</span> = <span class="sp-syntax-punctuation">[</span>
<span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'Cabbage'</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">isFruit</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">false</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">1</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">,</span>
<span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'Garlic'</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">isFruit</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">false</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">2</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">,</span>
<span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-string">'Apple'</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">isFruit</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">true</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-static">3</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">,</span>
<span class="sp-syntax-punctuation">]</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">ShoppingList</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">const</span> <span class="sp-syntax-plain">listItems</span> = <span class="sp-syntax-plain">products</span>.<span class="sp-syntax-property">map</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">product</span> <span class="sp-syntax-punctuation">=></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">li</span>
<span class="sp-syntax-property">key</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">product</span>.<span class="sp-syntax-property">id</span><span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-property">style</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-property">color</span><span class="sp-syntax-punctuation">:</span> <span class="sp-syntax-plain">product</span>.<span class="sp-syntax-property">isFruit</span> ? <span class="sp-syntax-string">'magenta'</span> : <span class="sp-syntax-string">'darkgreen'</span>
<span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">product</span>.<span class="sp-syntax-property">title</span><span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">li</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">ul</span><span class="sp-syntax-punctuation">></span><span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">listItems</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">ul</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
</pre></div></div></div><div class=" order-last xl:order-2 sp-stack"><div class="p-0 sm:p-2 md:p-4 lg:p-8 bg-card dark:bg-wash-dark h-full relative md:rounded-b-lg lg:rounded-b-none"><div style="position:relative"><iframe class="rounded-t-none bg-white md:shadow-md sm:rounded-lg w-full max-w-full transition-opacity absolute opacity-0 pointer-events-none duration-75" title="Sandbox Preview" style="height:15px;z-index:-1"></iframe></div></div></div><button translate="yes" class="sandpack-expand flex text-base justify-between dark:border-card-dark bg-wash dark:bg-card-dark items-center z-10 p-1 w-full order-2 xl:order-last border-b-1 relative top-0"><span class="flex p-2 focus:outline-none text-primary dark:text-primary-dark leading-[20px]"><svg class="rotate-0 inline me-1.5 text-xl" xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg>Show more</span></button></div></div></div></div><!--/$--><div class="max-w-4xl ms-0 2xl:mx-auto">
<h2 id="responding-to-events" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Responding to events <a href="#responding-to-events" aria-label="Link for Responding to events " title="Link for Responding to events " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">You can respond to events by declaring <em>event handler</em> functions inside your components:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">handleClick</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-definition">alert</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-string">'You clicked me!'</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">button</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">handleClick</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> Click me<br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Notice how <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">onClick={handleClick}</code> has no parentheses at the end! Do not <em>call</em> the event handler function: you only need to <em>pass it down</em>. React will call your event handler when the user clicks the button.</p>
<h2 id="updating-the-screen" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Updating the screen <a href="#updating-the-screen" aria-label="Link for Updating the screen " title="Link for Updating the screen " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">Often, you’ll want your component to “remember” some information and display it. For example, maybe you want to count the number of times a button is clicked. To do this, add <em>state</em> to your component.</p>
<p class="whitespace-pre-wrap my-4">First, import <a class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal" href="/reference/react/useState"><code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">useState</code></a> from React:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">import</span> <span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-plain">useState</span> <span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-keyword">from</span> <span class="sp-syntax-string">'react'</span><span class="sp-syntax-punctuation">;</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Now you can declare a <em>state variable</em> inside your component:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-keyword">const</span> <span class="sp-syntax-punctuation">[</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-plain">setCount</span><span class="sp-syntax-punctuation">]</span> = <span class="sp-syntax-definition">useState</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-static">0</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "> <span class="sp-syntax-comment">// ...</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">You’ll get two things from <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">useState</code>: the current state (<code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code>), and the function that lets you update it (<code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">setCount</code>). You can give them any names, but the convention is to write <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">[something, setSomething]</code>.</p>
<p class="whitespace-pre-wrap my-4">The first time the button is displayed, <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> will be <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">0</code> because you passed <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">0</code> to <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">useState()</code>. When you want to change state, call <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">setCount()</code> and pass the new value to it. Clicking this button will increment the counter:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-keyword">const</span> <span class="sp-syntax-punctuation">[</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-plain">setCount</span><span class="sp-syntax-punctuation">]</span> = <span class="sp-syntax-definition">useState</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-static">0</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><br></div><div class="cm-line "> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">handleClick</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-definition">setCount</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">count</span> + <span class="sp-syntax-static">1</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">button</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">handleClick</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> Clicked <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> times<br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">React will call your component function again. This time, <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> will be <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">1</code>. Then it will be <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">2</code>. And so on.</p>
<p class="whitespace-pre-wrap my-4">If you render the same component multiple times, each will get its own state. Click each button separately:</p>
</div><!--$--><div class="sandpack sandpack--playground w-full my-8" dir="ltr"><div class="sp-wrapper"><div class="shadow-lg dark:shadow-lg-dark rounded-lg" style="contain:content"><div class="bg-wash dark:bg-card-dark flex justify-between items-center relative z-10 border-b border-border dark:border-border-dark rounded-t-lg text-lg"><div class="flex-1 grow min-w-0 px-4 lg:px-6"><div><div class="relative overflow-hidden"><div class="w-[fit-content] invisible"><div class=" sp-tabs" translate="no"><div aria-label="Select active file" class=" sp-tabs-scrollable-container" role="tablist"><button aria-selected="true" class=" sp-tab-button" data-active="true" role="tab" title="/src/App.js" type="button">App.js</button></div></div></div><button class="absolute top-0 start-[2px]" id="headlessui-listbox-button-:R9iocq6:" aria-haspopup="true" aria-expanded="false" data-headlessui-state="" type="button"><span class="h-full py-2 px-1 mt-px -mb-px flex border-b text-link dark:text-link-dark 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for App.js" aria-multiline="true" class="sp-pristine sp-javascript sp-cm" role="textbox" tabindex="0" translate="no"><pre class=" sp-pre-placeholder" style="margin-left:var(--sp-space-11)"><span class="sp-syntax-keyword">import</span> <span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-plain">useState</span> <span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-keyword">from</span> <span class="sp-syntax-string">'react'</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyApp</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>Counters that update separately<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-punctuation">/></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-punctuation">/></span>
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">const</span> <span class="sp-syntax-punctuation">[</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-plain">setCount</span><span class="sp-syntax-punctuation">]</span> = <span class="sp-syntax-definition">useState</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-static">0</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">handleClick</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-definition">setCount</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">count</span> + <span class="sp-syntax-static">1</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">button</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">handleClick</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">></span>
Clicked <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> times
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
</pre></div></div></div><div class=" order-last xl:order-2 sp-stack"><div class="p-0 sm:p-2 md:p-4 lg:p-8 bg-card dark:bg-wash-dark h-full relative md:rounded-b-lg lg:rounded-b-none"><div style="position:relative"><iframe class="rounded-t-none bg-white md:shadow-md sm:rounded-lg w-full max-w-full transition-opacity absolute opacity-0 pointer-events-none duration-75" title="Sandbox Preview" style="height:15px;z-index:-1"></iframe></div></div></div><button translate="yes" class="sandpack-expand flex text-base justify-between dark:border-card-dark bg-wash dark:bg-card-dark items-center z-10 p-1 w-full order-2 xl:order-last border-b-1 relative top-0"><span class="flex p-2 focus:outline-none text-primary dark:text-primary-dark leading-[20px]"><svg class="rotate-0 inline me-1.5 text-xl" xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg>Show more</span></button></div></div></div></div><!--/$--><div class="max-w-4xl ms-0 2xl:mx-auto">
<p class="whitespace-pre-wrap my-4">Notice how each button “remembers” its own <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> state and doesn’t affect other buttons.</p>
<h2 id="using-hooks" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Using Hooks <a href="#using-hooks" aria-label="Link for Using Hooks " title="Link for Using Hooks " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">Functions starting with <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">use</code> are called <em>Hooks</em>. <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">useState</code> is a built-in Hook provided by React. You can find other built-in Hooks in the <a class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal" href="/reference/react">API reference.</a> You can also write your own Hooks by combining the existing ones.</p>
<p class="whitespace-pre-wrap my-4">Hooks are more restrictive than other functions. You can only call Hooks <em>at the top</em> of your components (or other Hooks). If you want to use <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">useState</code> in a condition or a loop, extract a new component and put it there.</p>
<h2 id="sharing-data-between-components" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Sharing data between components <a href="#sharing-data-between-components" aria-label="Link for Sharing data between components " title="Link for Sharing data between components " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">In the previous example, each <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code> had its own independent <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code>, and when each button was clicked, only the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> for the button clicked changed:</p>
<div class="flex flex-col sm:flex-row py-2 sm:p-0 sm:space-y-0 justify-center items-start sm:items-center w-full"><figure class="flex flex-col px-0 p-0 sm:p-10 first:mt-0 mt-10 sm:mt-0 justify-center items-center"><div class="dark-image"><img alt="Diagram showing a tree of three components, one parent labeled MyApp and two children labeled MyButton. Both MyButton components contain a count with value zero." loading="lazy" width="407" height="367" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child.dark.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child.dark.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child.dark.png&w=828&q=75"></div><div class="light-image"><img alt="Diagram showing a tree of three components, one parent labeled MyApp and two children labeled MyButton. Both MyButton components contain a count with value zero." loading="lazy" width="407" height="367" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child.png&w=828&q=75"></div><div class="w-full table"><figcaption class="p-1 sm:p-2 mt-0 sm:mt-0 text-gray-40 text-base lg:text-lg text-center leading-tight table-caption"><p class="whitespace-pre-wrap my-4">Initially, each <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code>’s <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> state is <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">0</code></p></figcaption></div></figure><figure class="flex flex-col px-0 p-0 sm:p-10 first:mt-0 mt-10 sm:mt-0 justify-center items-center"><div class="dark-image"><img alt="The same diagram as the previous, with the count of the first child MyButton component highlighted indicating a click with the count value incremented to one. The second MyButton component still contains value zero." loading="lazy" width="407" height="367" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child_clicked.dark.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child_clicked.dark.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child_clicked.dark.png&w=828&q=75"></div><div class="light-image"><img alt="The same diagram as the previous, with the count of the first child MyButton component highlighted indicating a click with the count value incremented to one. The second MyButton component still contains value zero." loading="lazy" width="407" height="367" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child_clicked.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child_clicked.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_child_clicked.png&w=828&q=75"></div><div class="w-full table"><figcaption class="p-1 sm:p-2 mt-0 sm:mt-0 text-gray-40 text-base lg:text-lg text-center leading-tight table-caption"><p class="whitespace-pre-wrap my-4">The first <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code> updates its <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> to <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">1</code></p></figcaption></div></figure></div>
<p class="whitespace-pre-wrap my-4">However, often you’ll need components to <em>share data and always update together</em>.</p>
<p class="whitespace-pre-wrap my-4">To make both <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code> components display the same <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> and update together, you need to move the state from the individual buttons “upwards” to the closest component containing all of them.</p>
<p class="whitespace-pre-wrap my-4">In this example, it is <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code>:</p>
<div class="flex flex-col sm:flex-row py-2 sm:p-0 sm:space-y-0 justify-center items-start sm:items-center w-full"><figure class="flex flex-col px-0 p-0 sm:p-10 first:mt-0 mt-10 sm:mt-0 justify-center items-center"><div class="dark-image"><img alt="Diagram showing a tree of three components, one parent labeled MyApp and two children labeled MyButton. MyApp contains a count value of zero which is passed down to both of the MyButton components, which also show value zero." loading="lazy" width="410" height="385" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent.dark.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent.dark.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent.dark.png&w=828&q=75"></div><div class="light-image"><img alt="Diagram showing a tree of three components, one parent labeled MyApp and two children labeled MyButton. MyApp contains a count value of zero which is passed down to both of the MyButton components, which also show value zero." loading="lazy" width="410" height="385" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent.png&w=828&q=75"></div><div class="w-full table"><figcaption class="p-1 sm:p-2 mt-0 sm:mt-0 text-gray-40 text-base lg:text-lg text-center leading-tight table-caption"><p class="whitespace-pre-wrap my-4">Initially, <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code>’s <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> state is <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">0</code> and is passed down to both children</p></figcaption></div></figure><figure class="flex flex-col px-0 p-0 sm:p-10 first:mt-0 mt-10 sm:mt-0 justify-center items-center"><div class="dark-image"><img alt="The same diagram as the previous, with the count of the parent MyApp component highlighted indicating a click with the value incremented to one. The flow to both of the children MyButton components is also highlighted, and the count value in each child is set to one indicating the value was passed down." loading="lazy" width="410" height="385" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent_clicked.dark.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent_clicked.dark.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent_clicked.dark.png&w=828&q=75"></div><div class="light-image"><img alt="The same diagram as the previous, with the count of the parent MyApp component highlighted indicating a click with the value incremented to one. The flow to both of the children MyButton components is also highlighted, and the count value in each child is set to one indicating the value was passed down." loading="lazy" width="410" height="385" decoding="async" data-nimg="1" style="color:transparent" srcset="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent_clicked.png&w=640&q=75 1x, /_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent_clicked.png&w=828&q=75 2x" src="/_next/image?url=%2Fimages%2Fdocs%2Fdiagrams%2Fsharing_data_parent_clicked.png&w=828&q=75"></div><div class="w-full table"><figcaption class="p-1 sm:p-2 mt-0 sm:mt-0 text-gray-40 text-base lg:text-lg text-center leading-tight table-caption"><p class="whitespace-pre-wrap my-4">On click, <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code> updates its <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> state to <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">1</code> and passes it down to both children</p></figcaption></div></figure></div>
<p class="whitespace-pre-wrap my-4">Now when you click either button, the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> in <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code> will change, which will change both of the counts in <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code>. Here’s how you can express this in code.</p>
<p class="whitespace-pre-wrap my-4">First, <em>move the state up</em> from <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code> into <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code>:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyApp</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-keyword">const</span> <span class="sp-syntax-punctuation">[</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-plain">setCount</span><span class="sp-syntax-punctuation">]</span> = <span class="sp-syntax-definition">useState</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-static">0</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">handleClick</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-definition">setCount</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">count</span> + <span class="sp-syntax-static">1</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>Counters that update separately<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><br></div><div class="cm-line "><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-comment">// ... we're moving code from here ...</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">Then, <em>pass the state down</em> from <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code> to each <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code>, together with the shared click handler. You can pass information to <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code> using the JSX curly braces, just like you previously did with built-in tags like <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px"><img></code>:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line "><span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyApp</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-keyword">const</span> <span class="sp-syntax-punctuation">[</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-plain">setCount</span><span class="sp-syntax-punctuation">]</span> = <span class="sp-syntax-definition">useState</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-static">0</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><br></div><div class="cm-line "> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">handleClick</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-definition">setCount</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">count</span> + <span class="sp-syntax-static">1</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">}</span><br></div><div class="cm-line "><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>Counters that update together<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-property">count</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">handleClick</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-property">count</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">handleClick</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-punctuation">/></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">The information you pass down like this is called <em>props</em>. Now the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code> component contains the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> state and the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">handleClick</code> event handler, and <em>passes both of them down as props</em> to each of the buttons.</p>
<p class="whitespace-pre-wrap my-4">Finally, change <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyButton</code> to <em>read</em> the props you have passed from its parent component:</p>
<!--$--><div dir="ltr" class="sandpack sandpack--codeblock rounded-2xl h-full w-full overflow-x-auto flex items-center bg-wash dark:bg-gray-95 shadow-lg my-8" style="contain:content"><div class="sp-wrapper"><div class="sp-stack"><div class="sp-code-editor"><pre class="sp-cm sp-pristine sp-javascript flex align-start"><code class="sp-pre-placeholder grow-[2]"><div class="cm-line bg-github-highlight dark:bg-opacity-10"><span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">onClick</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span><br></div><div class="cm-line "> <span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span><br></div><div class="cm-line bg-github-highlight dark:bg-opacity-10"> <span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">button</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">onClick</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> Clicked <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> times<br></div><div class="cm-line "> <span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span><br></div><div class="cm-line "> <span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span><br></div><div class="cm-line "><span class="sp-syntax-punctuation">}</span></div></code></pre></div></div></div></div><!--/$-->
<p class="whitespace-pre-wrap my-4">When you click the button, the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">onClick</code> handler fires. Each button’s <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">onClick</code> prop was set to the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">handleClick</code> function inside <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">MyApp</code>, so the code inside of it runs. That code calls <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">setCount(count + 1)</code>, incrementing the <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> state variable. The new <code dir="ltr" class="inline text-code text-secondary dark:text-secondary-dark px-1 rounded-md no-underline bg-gray-30 bg-opacity-10 py-px">count</code> value is passed as a prop to each button, so they all show the new value. This is called “lifting state up”. By moving state up, you’ve shared it between components.</p>
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for App.js" aria-multiline="true" class="sp-pristine sp-javascript sp-cm" role="textbox" tabindex="0" translate="no"><pre class=" sp-pre-placeholder" style="margin-left:var(--sp-space-11)"><span class="sp-syntax-keyword">import</span> <span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-plain">useState</span> <span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-keyword">from</span> <span class="sp-syntax-string">'react'</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-keyword">export</span> <span class="sp-syntax-keyword">default</span> <span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyApp</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">const</span> <span class="sp-syntax-punctuation">[</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-plain">setCount</span><span class="sp-syntax-punctuation">]</span> = <span class="sp-syntax-definition">useState</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-static">0</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">handleClick</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-definition">setCount</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-plain">count</span> + <span class="sp-syntax-static">1</span><span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>Counters that update together<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">h1</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-property">count</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">handleClick</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-punctuation">/></span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-definition">MyButton</span> <span class="sp-syntax-property">count</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">handleClick</span><span class="sp-syntax-punctuation">}</span> <span class="sp-syntax-punctuation">/></span>
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">div</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
<span class="sp-syntax-keyword">function</span> <span class="sp-syntax-definition">MyButton</span><span class="sp-syntax-punctuation">(</span><span class="sp-syntax-punctuation">{</span> <span class="sp-syntax-property">count</span><span class="sp-syntax-punctuation">,</span> <span class="sp-syntax-property">onClick</span> <span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">)</span> <span class="sp-syntax-punctuation">{</span>
<span class="sp-syntax-keyword">return</span> <span class="sp-syntax-punctuation">(</span>
<span class="sp-syntax-punctuation"><</span><span class="sp-syntax-tag">button</span> <span class="sp-syntax-property">onClick</span>=<span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">onClick</span><span class="sp-syntax-punctuation">}</span><span class="sp-syntax-punctuation">></span>
Clicked <span class="sp-syntax-punctuation">{</span><span class="sp-syntax-plain">count</span><span class="sp-syntax-punctuation">}</span> times
<span class="sp-syntax-punctuation"></</span><span class="sp-syntax-tag">button</span><span class="sp-syntax-punctuation">></span>
<span class="sp-syntax-punctuation">)</span><span class="sp-syntax-punctuation">;</span>
<span class="sp-syntax-punctuation">}</span>
</pre></div></div></div><div class=" order-last xl:order-2 sp-stack"><div class="p-0 sm:p-2 md:p-4 lg:p-8 bg-card dark:bg-wash-dark h-full relative md:rounded-b-lg lg:rounded-b-none"><div style="position:relative"><iframe class="rounded-t-none bg-white md:shadow-md sm:rounded-lg w-full max-w-full transition-opacity absolute opacity-0 pointer-events-none duration-75" title="Sandbox Preview" style="height:15px;z-index:-1"></iframe></div></div></div><button translate="yes" class="sandpack-expand flex text-base justify-between dark:border-card-dark bg-wash dark:bg-card-dark items-center z-10 p-1 w-full order-2 xl:order-last border-b-1 relative top-0"><span class="flex p-2 focus:outline-none text-primary dark:text-primary-dark leading-[20px]"><svg class="rotate-0 inline me-1.5 text-xl" xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 20 20"><g fill="none" fill-rule="evenodd" transform="translate(-446 -398)"><path fill="currentColor" fill-rule="nonzero" d="M95.8838835,240.366117 C95.3957281,239.877961 94.6042719,239.877961 94.1161165,240.366117 C93.6279612,240.854272 93.6279612,241.645728 94.1161165,242.133883 L98.6161165,246.633883 C99.1042719,247.122039 99.8957281,247.122039 100.383883,246.633883 L104.883883,242.133883 C105.372039,241.645728 105.372039,240.854272 104.883883,240.366117 C104.395728,239.877961 103.604272,239.877961 103.116117,240.366117 L99.5,243.982233 L95.8838835,240.366117 Z" transform="translate(356.5 164.5)"></path><polygon points="446 418 466 418 466 398 446 398"></polygon></g></svg>Show more</span></button></div></div></div></div><!--/$--><div class="max-w-4xl ms-0 2xl:mx-auto">
<h2 id="next-steps" class="mdx-heading text-3xl font-display leading-10 text-primary dark:text-primary-dark font-bold my-6">Next Steps <a href="#next-steps" aria-label="Link for Next Steps " title="Link for Next Steps " class="mdx-header-anchor inline-block"><svg width="1em" height="1em" viewBox="0 0 13 13" xmlns="http://www.w3.org/2000/svg" class="text-gray-70 ms-2 h-5 w-5"><g fill="currentColor" fill-rule="evenodd"><path d="M7.778 7.975a2.5 2.5 0 0 0 .347-3.837L6.017 2.03a2.498 2.498 0 0 0-3.542-.007 2.5 2.5 0 0 0 .006 3.543l1.153 1.15c.07-.29.154-.563.25-.773.036-.077.084-.16.14-.25L3.18 4.85a1.496 1.496 0 0 1 .002-2.12 1.496 1.496 0 0 1 2.12 0l2.124 2.123a1.496 1.496 0 0 1-.333 2.37c.16.246.42.504.685.752z"></path><path d="M5.657 4.557a2.5 2.5 0 0 0-.347 3.837l2.108 2.108a2.498 2.498 0 0 0 3.542.007 2.5 2.5 0 0 0-.006-3.543L9.802 5.815c-.07.29-.154.565-.25.774-.036.076-.084.16-.14.25l.842.84c.585.587.59 1.532 0 2.122-.587.585-1.532.59-2.12 0L6.008 7.68a1.496 1.496 0 0 1 .332-2.372c-.16-.245-.42-.503-.685-.75z"></path></g></svg></a></h2>
<p class="whitespace-pre-wrap my-4">By now, you know the basics of how to write React code!</p>
<p class="whitespace-pre-wrap my-4">Check out the <a class="inline text-link dark:text-link-dark border-b border-link border-opacity-0 hover:border-opacity-100 duration-100 ease-in transition leading-normal" href="/learn/tutorial-tic-tac-toe">Tutorial</a> to put them into practice and build your first mini-app with React.</p></div></div><div class="grid grid-cols-1 gap-4 py-4 mx-auto max-w-7xl md:grid-cols-2 md:py-12"><div></div><a class="flex gap-x-4 md:gap-x-6 items-center w-full md:min-w-80 md:w-fit md:max-w-md px-4 md:px-5 py-6 border-2 border-transparent text-base leading-base text-link dark:text-link-dark rounded-lg group focus:text-link dark:focus:text-link-dark focus:bg-highlight focus:border-link dark:focus:bg-highlight-dark dark:focus:border-link-dark focus:border-opacity-100 focus:border-2 focus:ring-1 focus:ring-offset-4 focus:ring-blue-40 active:ring-0 active:ring-offset-0 hover:bg-gray-5 dark:hover:bg-gray-80 flex-row-reverse justify-self-end text-end" 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stop-color="#0080F9"></stop></linearGradient><linearGradient id="paint10_linear_627_396207" x1="14.4218" y1="14.2915" x2="15.7366" y2="14.2915" gradientUnits="userSpaceOnUse"><stop stop-color="#0377EF"></stop><stop offset="0.9994" stop-color="#0279F1"></stop></linearGradient><linearGradient id="paint11_linear_627_396207" x1="13.2783" y1="13.5675" x2="14.2235" y2="14.1236" gradientUnits="userSpaceOnUse"><stop offset="0.0019" stop-color="#0471E9"></stop><stop offset="1" stop-color="#0377EF"></stop></linearGradient><linearGradient id="paint12_linear_627_396207" x1="10.3961" y1="9.46696" x2="13.424" y2="13.274" gradientUnits="userSpaceOnUse"><stop offset="0.2765" stop-color="#0867DF"></stop><stop offset="1" stop-color="#0471E9"></stop></linearGradient></defs></svg></div></a><div class="text-xs text-left rtl:text-right mt-2 pe-0.5" dir="ltr">Copyright © Meta Platforms, Inc</div><div class="uwu-visible text-xs cursor-pointer hover:text-link hover:dark:text-link-dark hover:underline">no uwu 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10 0"></path></svg></a></div></div></div></footer></div></div></main><!--/$--><div class="hidden -mt-16 lg:max-w-custom-xs 2xl:block"><nav role="navigation" class="pt-20 sticky top-0 end-0"><h2 class="mb-3 lg:mb-3 uppercase tracking-wide font-bold text-sm text-secondary dark:text-secondary-dark px-4 w-full">On this page</h2><div class="h-full overflow-y-auto ps-4 max-h-[calc(100vh-7.5rem)]" style="overscroll-behavior:contain"><ul class="space-y-2 pb-16"><li class="text-sm px-2 rounded-s-xl bg-highlight dark:bg-highlight-dark"><a class="text-link dark:text-link-dark font-bold block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#">Overview</a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#components">Creating and nesting components </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#writing-markup-with-jsx">Writing markup with JSX </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#adding-styles">Adding styles </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#displaying-data">Displaying data </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#conditional-rendering">Conditional rendering </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#rendering-lists">Rendering lists </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#responding-to-events">Responding to events </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#updating-the-screen">Updating the screen </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#using-hooks">Using Hooks </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#sharing-data-between-components">Sharing data between components </a></li><li class="text-sm px-2 rounded-s-xl"><a class="text-secondary dark:text-secondary-dark block hover:text-link dark:hover:text-link-dark leading-normal py-2" href="#next-steps">Next Steps </a></li></ul></div></nav></div></div></div><script id="__NEXT_DATA__" type="application/json">{"props":{"pageProps":{"toc":"[{\"url\":\"#\",\"text\":\"Overview\",\"depth\":2},{\"url\":\"#components\",\"depth\":2,\"text\":\"Creating and nesting components \"},{\"url\":\"#writing-markup-with-jsx\",\"depth\":2,\"text\":\"Writing markup with JSX \"},{\"url\":\"#adding-styles\",\"depth\":2,\"text\":\"Adding styles \"},{\"url\":\"#displaying-data\",\"depth\":2,\"text\":\"Displaying data \"},{\"url\":\"#conditional-rendering\",\"depth\":2,\"text\":\"Conditional rendering \"},{\"url\":\"#rendering-lists\",\"depth\":2,\"text\":\"Rendering lists \"},{\"url\":\"#responding-to-events\",\"depth\":2,\"text\":\"Responding to events \"},{\"url\":\"#updating-the-screen\",\"depth\":2,\"text\":\"Updating the screen \"},{\"url\":\"#using-hooks\",\"depth\":2,\"text\":\"Using Hooks \"},{\"url\":\"#sharing-data-between-components\",\"depth\":2,\"text\":\"Sharing data between components \"},{\"url\":\"#next-steps\",\"depth\":2,\"text\":\"Next Steps \"}]","content":"[[\"$r\",\"MaxWidth\",\"20\",{\"children\":[[\"$r\",\"Intro\",null,{\"children\":[\"$r\",\"p\",null,{\"children\":\"Welcome to the React documentation! This page will give you an introduction to the 80% of React concepts that you will use on a daily basis.\"}]}],\"\\n\",[\"$r\",\"YouWillLearn\",null,{\"children\":[\"$r\",\"ul\",null,{\"children\":[\"\\n\",[\"$r\",\"li\",null,{\"children\":\"How to create and nest components\"}],\"\\n\",[\"$r\",\"li\",null,{\"children\":\"How to add markup and styles\"}],\"\\n\",[\"$r\",\"li\",null,{\"children\":\"How to display data\"}],\"\\n\",[\"$r\",\"li\",null,{\"children\":\"How to render conditions and lists\"}],\"\\n\",[\"$r\",\"li\",null,{\"children\":\"How to respond to events and update the screen\"}],\"\\n\",[\"$r\",\"li\",null,{\"children\":\"How to share data between components\"}],\"\\n\"]}]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"components\",\"children\":\"Creating and nesting components \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"React apps are made out of \",[\"$r\",\"em\",null,{\"children\":\"components\"}],\". A component is a piece of the UI (user interface) that has its own logic and appearance. A component can be as small as a button, or as large as an entire page.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":\"React components are JavaScript functions that return markup:\"}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"function MyButton() {\\n return (\\n \u003cbutton\u003eI'm a button\u003c/button\u003e\\n );\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Now that you’ve declared \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\", you can nest it into another component:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{5}\",\"children\":\"export default function MyApp() {\\n return (\\n \u003cdiv\u003e\\n \u003ch1\u003eWelcome to my app\u003c/h1\u003e\\n \u003cMyButton /\u003e\\n \u003c/div\u003e\\n );\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Notice that \",[\"$r\",\"code\",null,{\"children\":\"\u003cMyButton /\u003e\"}],\" starts with a capital letter. 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All of the \",[\"$r\",\"a\",null,{\"href\":\"/learn/installation\",\"children\":\"tools we recommend for local development\"}],\" support JSX out of the box.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"JSX is stricter than HTML. You have to close tags like \",[\"$r\",\"code\",null,{\"children\":\"\u003cbr /\u003e\"}],\". Your component also can’t return multiple JSX tags. You have to wrap them into a shared parent, like a \",[\"$r\",\"code\",null,{\"children\":\"\u003cdiv\u003e...\u003c/div\u003e\"}],\" or an empty \",[\"$r\",\"code\",null,{\"children\":\"\u003c\u003e...\u003c/\u003e\"}],\" wrapper:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{3,6}\",\"children\":\"function AboutPage() {\\n return (\\n \u003c\u003e\\n \u003ch1\u003eAbout\u003c/h1\u003e\\n \u003cp\u003eHello there.\u003cbr /\u003eHow do you do?\u003c/p\u003e\\n \u003c/\u003e\\n );\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"If you have a lot of HTML to port to JSX, you can use an \",[\"$r\",\"a\",null,{\"href\":\"https://transform.tools/html-to-jsx\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":\"online converter.\"}]]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"adding-styles\",\"children\":\"Adding styles \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"In React, you specify a CSS class with \",[\"$r\",\"code\",null,{\"children\":\"className\"}],\". It works the same way as the HTML \",[\"$r\",\"a\",null,{\"href\":\"https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/class\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":[\"$r\",\"code\",null,{\"children\":\"class\"}]}],\" attribute:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"\u003cimg className=\\\"avatar\\\" /\u003e\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":\"Then you write the CSS rules for it in a separate CSS file:\"}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-css\",\"children\":\"/* In your CSS */\\n.avatar {\\n border-radius: 50%;\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"React does not prescribe how you add CSS files. In the simplest case, you’ll add a \",[\"$r\",\"a\",null,{\"href\":\"https://developer.mozilla.org/en-US/docs/Web/HTML/Element/link\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":[\"$r\",\"code\",null,{\"children\":\"\u003clink\u003e\"}]}],\" tag to your HTML. If you use a build tool or a framework, consult its documentation to learn how to add a CSS file to your project.\"]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"displaying-data\",\"children\":\"Displaying data \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"JSX lets you put markup into JavaScript. Curly braces let you “escape back” into JavaScript so that you can embed some variable from your code and display it to the user. For example, this will display \",[\"$r\",\"code\",null,{\"children\":\"user.name\"}],\":\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{3}\",\"children\":\"return (\\n \u003ch1\u003e\\n {user.name}\\n \u003c/h1\u003e\\n);\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"You can also “escape into JavaScript” from JSX attributes, but you have to use curly braces \",[\"$r\",\"em\",null,{\"children\":\"instead of\"}],\" quotes. For example, \",[\"$r\",\"code\",null,{\"children\":\"className=\\\"avatar\\\"\"}],\" passes the \",[\"$r\",\"code\",null,{\"children\":\"\\\"avatar\\\"\"}],\" string as the CSS class, but \",[\"$r\",\"code\",null,{\"children\":\"src={user.imageUrl}\"}],\" reads the JavaScript \",[\"$r\",\"code\",null,{\"children\":\"user.imageUrl\"}],\" variable value, and then passes that value as the \",[\"$r\",\"code\",null,{\"children\":\"src\"}],\" attribute:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{3,4}\",\"children\":\"return (\\n \u003cimg\\n className=\\\"avatar\\\"\\n src={user.imageUrl}\\n /\u003e\\n);\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"You can put more complex expressions inside the JSX curly braces too, for example, \",[\"$r\",\"a\",null,{\"href\":\"https://javascript.info/operators#string-concatenation-with-binary\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":\"string concatenation\"}],\":\"]}],\"\\n\"]}],[\"$r\",\"Sandpack\",null,{\"children\":[[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"const user = {\\n name: 'Hedy Lamarr',\\n imageUrl: 'https://i.imgur.com/yXOvdOSs.jpg',\\n imageSize: 90,\\n};\\n\\nexport default function Profile() {\\n return (\\n \u003c\u003e\\n \u003ch1\u003e{user.name}\u003c/h1\u003e\\n \u003cimg\\n className=\\\"avatar\\\"\\n src={user.imageUrl}\\n alt={'Photo of ' + user.name}\\n style={{\\n width: user.imageSize,\\n height: user.imageSize\\n }}\\n /\u003e\\n \u003c/\u003e\\n );\\n}\\n\"}]}],[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-css\",\"children\":\".avatar {\\n border-radius: 50%;\\n}\\n\\n.large {\\n border: 4px solid gold;\\n}\\n\"}]}]]}],[\"$r\",\"MaxWidth\",\"92\",{\"children\":[\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"In the above example, \",[\"$r\",\"code\",null,{\"children\":\"style={{}}\"}],\" is not a special syntax, but a regular \",[\"$r\",\"code\",null,{\"children\":\"{}\"}],\" object inside the \",[\"$r\",\"code\",null,{\"children\":\"style={ }\"}],\" JSX curly braces. You can use the \",[\"$r\",\"code\",null,{\"children\":\"style\"}],\" attribute when your styles depend on JavaScript variables.\"]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"conditional-rendering\",\"children\":\"Conditional rendering \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"In React, there is no special syntax for writing conditions. Instead, you’ll use the same techniques as you use when writing regular JavaScript code. For example, you can use an \",[\"$r\",\"a\",null,{\"href\":\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":[\"$r\",\"code\",null,{\"children\":\"if\"}]}],\" statement to conditionally include JSX:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"let content;\\nif (isLoggedIn) {\\n content = \u003cAdminPanel /\u003e;\\n} else {\\n content = \u003cLoginForm /\u003e;\\n}\\nreturn (\\n \u003cdiv\u003e\\n {content}\\n \u003c/div\u003e\\n);\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"If you prefer more compact code, you can use the \",[\"$r\",\"a\",null,{\"href\":\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":[\"conditional \",[\"$r\",\"code\",null,{\"children\":\"?\"}],\" operator.\"]}],\" Unlike \",[\"$r\",\"code\",null,{\"children\":\"if\"}],\", it works inside JSX:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"\u003cdiv\u003e\\n {isLoggedIn ? (\\n \u003cAdminPanel /\u003e\\n ) : (\\n \u003cLoginForm /\u003e\\n )}\\n\u003c/div\u003e\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"When you don’t need the \",[\"$r\",\"code\",null,{\"children\":\"else\"}],\" branch, you can also use a shorter \",[\"$r\",\"a\",null,{\"href\":\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_AND#short-circuit_evaluation\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":[\"logical \",[\"$r\",\"code\",null,{\"children\":\"\u0026\u0026\"}],\" syntax\"]}],\":\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"\u003cdiv\u003e\\n {isLoggedIn \u0026\u0026 \u003cAdminPanel /\u003e}\\n\u003c/div\u003e\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"All of these approaches also work for conditionally specifying attributes. If you’re unfamiliar with some of this JavaScript syntax, you can start by always using \",[\"$r\",\"code\",null,{\"children\":\"if...else\"}],\".\"]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"rendering-lists\",\"children\":\"Rendering lists \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"You will rely on JavaScript features like \",[\"$r\",\"a\",null,{\"href\":\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":[[\"$r\",\"code\",null,{\"children\":\"for\"}],\" loop\"]}],\" and the \",[\"$r\",\"a\",null,{\"href\":\"https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map\",\"target\":\"_blank\",\"rel\":\"nofollow noopener noreferrer\",\"children\":[\"array \",[\"$r\",\"code\",null,{\"children\":\"map()\"}],\" function\"]}],\" to render lists of components.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":\"For example, let’s say you have an array of products:\"}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"const products = [\\n { title: 'Cabbage', id: 1 },\\n { title: 'Garlic', id: 2 },\\n { title: 'Apple', id: 3 },\\n];\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Inside your component, use the \",[\"$r\",\"code\",null,{\"children\":\"map()\"}],\" function to transform an array of products into an array of \",[\"$r\",\"code\",null,{\"children\":\"\u003cli\u003e\"}],\" items:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"const listItems = products.map(product =\u003e\\n \u003cli key={product.id}\u003e\\n {product.title}\\n \u003c/li\u003e\\n);\\n\\nreturn (\\n \u003cul\u003e{listItems}\u003c/ul\u003e\\n);\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Notice how \",[\"$r\",\"code\",null,{\"children\":\"\u003cli\u003e\"}],\" has a \",[\"$r\",\"code\",null,{\"children\":\"key\"}],\" attribute. For each item in a list, you should pass a string or a number that uniquely identifies that item among its siblings. Usually, a key should be coming from your data, such as a database ID. React uses your keys to know what happened if you later insert, delete, or reorder the items.\"]}],\"\\n\"]}],[\"$r\",\"Sandpack\",null,{\"children\":[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"const products = [\\n { title: 'Cabbage', isFruit: false, id: 1 },\\n { title: 'Garlic', isFruit: false, id: 2 },\\n { title: 'Apple', isFruit: true, id: 3 },\\n];\\n\\nexport default function ShoppingList() {\\n const listItems = products.map(product =\u003e\\n \u003cli\\n key={product.id}\\n style={{\\n color: product.isFruit ? 'magenta' : 'darkgreen'\\n }}\\n \u003e\\n {product.title}\\n \u003c/li\u003e\\n );\\n\\n return (\\n \u003cul\u003e{listItems}\u003c/ul\u003e\\n );\\n}\\n\"}]}]}],[\"$r\",\"MaxWidth\",\"124\",{\"children\":[\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"responding-to-events\",\"children\":\"Responding to events \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"You can respond to events by declaring \",[\"$r\",\"em\",null,{\"children\":\"event handler\"}],\" functions inside your components:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{2-4,7}\",\"children\":\"function MyButton() {\\n function handleClick() {\\n alert('You clicked me!');\\n }\\n\\n return (\\n \u003cbutton onClick={handleClick}\u003e\\n Click me\\n \u003c/button\u003e\\n );\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Notice how \",[\"$r\",\"code\",null,{\"children\":\"onClick={handleClick}\"}],\" has no parentheses at the end! Do not \",[\"$r\",\"em\",null,{\"children\":\"call\"}],\" the event handler function: you only need to \",[\"$r\",\"em\",null,{\"children\":\"pass it down\"}],\". React will call your event handler when the user clicks the button.\"]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"updating-the-screen\",\"children\":\"Updating the screen \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Often, you’ll want your component to “remember” some information and display it. For example, maybe you want to count the number of times a button is clicked. To do this, add \",[\"$r\",\"em\",null,{\"children\":\"state\"}],\" to your component.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"First, import \",[\"$r\",\"a\",null,{\"href\":\"/reference/react/useState\",\"children\":[\"$r\",\"code\",null,{\"children\":\"useState\"}]}],\" from React:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"import { useState } from 'react';\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Now you can declare a \",[\"$r\",\"em\",null,{\"children\":\"state variable\"}],\" inside your component:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"function MyButton() {\\n const [count, setCount] = useState(0);\\n // ...\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"You’ll get two things from \",[\"$r\",\"code\",null,{\"children\":\"useState\"}],\": the current state (\",[\"$r\",\"code\",null,{\"children\":\"count\"}],\"), and the function that lets you update it (\",[\"$r\",\"code\",null,{\"children\":\"setCount\"}],\"). You can give them any names, but the convention is to write \",[\"$r\",\"code\",null,{\"children\":\"[something, setSomething]\"}],\".\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"The first time the button is displayed, \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" will be \",[\"$r\",\"code\",null,{\"children\":\"0\"}],\" because you passed \",[\"$r\",\"code\",null,{\"children\":\"0\"}],\" to \",[\"$r\",\"code\",null,{\"children\":\"useState()\"}],\". When you want to change state, call \",[\"$r\",\"code\",null,{\"children\":\"setCount()\"}],\" and pass the new value to it. Clicking this button will increment the counter:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{5}\",\"children\":\"function MyButton() {\\n const [count, setCount] = useState(0);\\n\\n function handleClick() {\\n setCount(count + 1);\\n }\\n\\n return (\\n \u003cbutton onClick={handleClick}\u003e\\n Clicked {count} times\\n \u003c/button\u003e\\n );\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"React will call your component function again. This time, \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" will be \",[\"$r\",\"code\",null,{\"children\":\"1\"}],\". Then it will be \",[\"$r\",\"code\",null,{\"children\":\"2\"}],\". And so on.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":\"If you render the same component multiple times, each will get its own state. Click each button separately:\"}],\"\\n\"]}],[\"$r\",\"Sandpack\",null,{\"children\":[[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"import { useState } from 'react';\\n\\nexport default function MyApp() {\\n return (\\n \u003cdiv\u003e\\n \u003ch1\u003eCounters that update separately\u003c/h1\u003e\\n \u003cMyButton /\u003e\\n \u003cMyButton /\u003e\\n \u003c/div\u003e\\n );\\n}\\n\\nfunction MyButton() {\\n const [count, setCount] = useState(0);\\n\\n function handleClick() {\\n setCount(count + 1);\\n }\\n\\n return (\\n \u003cbutton onClick={handleClick}\u003e\\n Clicked {count} times\\n \u003c/button\u003e\\n );\\n}\\n\"}]}],[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-css\",\"children\":\"button {\\n display: block;\\n margin-bottom: 5px;\\n}\\n\"}]}]]}],[\"$r\",\"MaxWidth\",\"166\",{\"children\":[\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Notice how each button “remembers” its own \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" state and doesn’t affect other buttons.\"]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"using-hooks\",\"children\":\"Using Hooks \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Functions starting with \",[\"$r\",\"code\",null,{\"children\":\"use\"}],\" are called \",[\"$r\",\"em\",null,{\"children\":\"Hooks\"}],\". \",[\"$r\",\"code\",null,{\"children\":\"useState\"}],\" is a built-in Hook provided by React. You can find other built-in Hooks in the \",[\"$r\",\"a\",null,{\"href\":\"/reference/react\",\"children\":\"API reference.\"}],\" You can also write your own Hooks by combining the existing ones.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Hooks are more restrictive than other functions. You can only call Hooks \",[\"$r\",\"em\",null,{\"children\":\"at the top\"}],\" of your components (or other Hooks). If you want to use \",[\"$r\",\"code\",null,{\"children\":\"useState\"}],\" in a condition or a loop, extract a new component and put it there.\"]}],\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"sharing-data-between-components\",\"children\":\"Sharing data between components \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"In the previous example, each \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\" had its own independent \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\", and when each button was clicked, only the \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" for the button clicked changed:\"]}],\"\\n\",[\"$r\",\"DiagramGroup\",null,{\"children\":[[\"$r\",\"Diagram\",null,{\"name\":\"sharing_data_child\",\"height\":367,\"width\":407,\"alt\":\"Diagram showing a tree of three components, one parent labeled MyApp and two children labeled MyButton. Both MyButton components contain a count with value zero.\",\"children\":[\"$r\",\"p\",null,{\"children\":[\"Initially, each \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\"’s \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" state is \",[\"$r\",\"code\",null,{\"children\":\"0\"}]]}]}],[\"$r\",\"Diagram\",null,{\"name\":\"sharing_data_child_clicked\",\"height\":367,\"width\":407,\"alt\":\"The same diagram as the previous, with the count of the first child MyButton component highlighted indicating a click with the count value incremented to one. The second MyButton component still contains value zero.\",\"children\":[\"$r\",\"p\",null,{\"children\":[\"The first \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\" updates its \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" to \",[\"$r\",\"code\",null,{\"children\":\"1\"}]]}]}]]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"However, often you’ll need components to \",[\"$r\",\"em\",null,{\"children\":\"share data and always update together\"}],\".\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"To make both \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\" components display the same \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" and update together, you need to move the state from the individual buttons “upwards” to the closest component containing all of them.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"In this example, it is \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\":\"]}],\"\\n\",[\"$r\",\"DiagramGroup\",null,{\"children\":[[\"$r\",\"Diagram\",null,{\"name\":\"sharing_data_parent\",\"height\":385,\"width\":410,\"alt\":\"Diagram showing a tree of three components, one parent labeled MyApp and two children labeled MyButton. MyApp contains a count value of zero which is passed down to both of the MyButton components, which also show value zero.\",\"children\":[\"$r\",\"p\",null,{\"children\":[\"Initially, \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\"’s \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" state is \",[\"$r\",\"code\",null,{\"children\":\"0\"}],\" and is passed down to both children\"]}]}],[\"$r\",\"Diagram\",null,{\"name\":\"sharing_data_parent_clicked\",\"height\":385,\"width\":410,\"alt\":\"The same diagram as the previous, with the count of the parent MyApp component highlighted indicating a click with the value incremented to one. The flow to both of the children MyButton components is also highlighted, and the count value in each child is set to one indicating the value was passed down.\",\"children\":[\"$r\",\"p\",null,{\"children\":[\"On click, \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\" updates its \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" state to \",[\"$r\",\"code\",null,{\"children\":\"1\"}],\" and passes it down to both children\"]}]}]]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Now when you click either button, the \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" in \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\" will change, which will change both of the counts in \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\". Here’s how you can express this in code.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"First, \",[\"$r\",\"em\",null,{\"children\":\"move the state up\"}],\" from \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\" into \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\":\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{2-6,18}\",\"children\":\"export default function MyApp() {\\n const [count, setCount] = useState(0);\\n\\n function handleClick() {\\n setCount(count + 1);\\n }\\n\\n return (\\n \u003cdiv\u003e\\n \u003ch1\u003eCounters that update separately\u003c/h1\u003e\\n \u003cMyButton /\u003e\\n \u003cMyButton /\u003e\\n \u003c/div\u003e\\n );\\n}\\n\\nfunction MyButton() {\\n // ... we're moving code from here ...\\n}\\n\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Then, \",[\"$r\",\"em\",null,{\"children\":\"pass the state down\"}],\" from \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\" to each \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\", together with the shared click handler. You can pass information to \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\" using the JSX curly braces, just like you previously did with built-in tags like \",[\"$r\",\"code\",null,{\"children\":\"\u003cimg\u003e\"}],\":\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{11-12}\",\"children\":\"export default function MyApp() {\\n const [count, setCount] = useState(0);\\n\\n function handleClick() {\\n setCount(count + 1);\\n }\\n\\n return (\\n \u003cdiv\u003e\\n \u003ch1\u003eCounters that update together\u003c/h1\u003e\\n \u003cMyButton count={count} onClick={handleClick} /\u003e\\n \u003cMyButton count={count} onClick={handleClick} /\u003e\\n \u003c/div\u003e\\n );\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"The information you pass down like this is called \",[\"$r\",\"em\",null,{\"children\":\"props\"}],\". Now the \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\" component contains the \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" state and the \",[\"$r\",\"code\",null,{\"children\":\"handleClick\"}],\" event handler, and \",[\"$r\",\"em\",null,{\"children\":\"passes both of them down as props\"}],\" to each of the buttons.\"]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Finally, change \",[\"$r\",\"code\",null,{\"children\":\"MyButton\"}],\" to \",[\"$r\",\"em\",null,{\"children\":\"read\"}],\" the props you have passed from its parent component:\"]}],\"\\n\",[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"meta\":\"{1,3}\",\"children\":\"function MyButton({ count, onClick }) {\\n return (\\n \u003cbutton onClick={onClick}\u003e\\n Clicked {count} times\\n \u003c/button\u003e\\n );\\n}\\n\"}]}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"When you click the button, the \",[\"$r\",\"code\",null,{\"children\":\"onClick\"}],\" handler fires. Each button’s \",[\"$r\",\"code\",null,{\"children\":\"onClick\"}],\" prop was set to the \",[\"$r\",\"code\",null,{\"children\":\"handleClick\"}],\" function inside \",[\"$r\",\"code\",null,{\"children\":\"MyApp\"}],\", so the code inside of it runs. That code calls \",[\"$r\",\"code\",null,{\"children\":\"setCount(count + 1)\"}],\", incrementing the \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" state variable. The new \",[\"$r\",\"code\",null,{\"children\":\"count\"}],\" value is passed as a prop to each button, so they all show the new value. This is called “lifting state up”. By moving state up, you’ve shared it between components.\"]}],\"\\n\"]}],[\"$r\",\"Sandpack\",null,{\"children\":[[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-js\",\"children\":\"import { useState } from 'react';\\n\\nexport default function MyApp() {\\n const [count, setCount] = useState(0);\\n\\n function handleClick() {\\n setCount(count + 1);\\n }\\n\\n return (\\n \u003cdiv\u003e\\n \u003ch1\u003eCounters that update together\u003c/h1\u003e\\n \u003cMyButton count={count} onClick={handleClick} /\u003e\\n \u003cMyButton count={count} onClick={handleClick} /\u003e\\n \u003c/div\u003e\\n );\\n}\\n\\nfunction MyButton({ count, onClick }) {\\n return (\\n \u003cbutton onClick={onClick}\u003e\\n Clicked {count} times\\n \u003c/button\u003e\\n );\\n}\\n\"}]}],[\"$r\",\"pre\",null,{\"children\":[\"$r\",\"code\",null,{\"className\":\"language-css\",\"children\":\"button {\\n display: block;\\n margin-bottom: 5px;\\n}\\n\"}]}]]}],[\"$r\",\"MaxWidth\",\"last\",{\"children\":[\"\\n\",[\"$r\",\"h2\",null,{\"id\":\"next-steps\",\"children\":\"Next Steps \"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":\"By now, you know the basics of how to write React code!\"}],\"\\n\",[\"$r\",\"p\",null,{\"children\":[\"Check out the \",[\"$r\",\"a\",null,{\"href\":\"/learn/tutorial-tic-tac-toe\",\"children\":\"Tutorial\"}],\" to put them into practice and build your first mini-app with React.\"]}]]}]]","meta":{"title":"Quick Start"},"languages":null},"__N_SSG":true},"page":"/[[...markdownPath]]","query":{"markdownPath":["learn"]},"buildId":"VtvJcdQtW_Z3z2Ex5E5Zx","isFallback":false,"gsp":true,"scriptLoader":[]}</script><next-route-announcer><p aria-live="assertive" id="__next-route-announcer__" role="alert" style="border: 0px; clip: rect(0px, 0px, 0px, 0px); height: 1px; margin: -1px; overflow: hidden; padding: 0px; position: absolute; top: 0px; width: 1px; white-space: nowrap; overflow-wrap: normal;"></p></next-route-announcer></body></html>