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| name = React
| logo = React Logo SVG.svg
| logo size =
| author = Jordan Walke
| developer = [[Meta Platforms|Meta]] and community
| released = {{Start date and age|2013|5|29}}<ref name="Occhino-2013">{{cite web|access-date=22 Oct 2018|first1=Tom|first2=Jordan|last1=Occhino|last2=Walke|title=JS Apps at Facebook|url=https://www.youtube.com/watch?v=GW0rj4sNH2w|website=YouTube|date=5 August 2013 |archive-date=31 May 2022|archive-url=https://web.archive.org/web/20220531133559/https://www.youtube.com/watch?v=GW0rj4sNH2w|url-status=live}}</ref>
| ver layout = stacked
| latest release version = {{wikidata|property|reference|edit|P348}}
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| genre = [[JavaScript library]]
| license = [[MIT License]]
| website = https://react.dev/
}}
'''React''' (also known as '''React.js''' or '''ReactJS''') is a [[free and open-source software|free and open-source]] [[frontend and backend|front-end]] [[JavaScript library]]<ref name="reactjs.org-3">{{Cite web |title=React – A JavaScript library for building user interfaces. |url=https://reactjs.org |url-status=live |access-date=7 April 2018 |website=reactjs.org |language=en-US |archive-date=April 8, 2018 |archive-url=https://web.archive.org/web/20180408084010/https://reactjs.org/ }}</ref><ref>{{Cite web |title=Chapter 1. What Is React? - What React Is and Why It Matters [Book] |url=https://www.oreilly.com/library/view/what-react-is/9781491996744/ch01.html |url-status=live |access-date=2023-05-06 |website=www.oreilly.com |language=en |archive-date=May 6, 2023 |archive-url=https://web.archive.org/web/20230506100446/https://www.oreilly.com/library/view/what-react-is/9781491996744/ch01.html }}</ref> that aims to make building [[user interface]]s based on [[component-based software engineering|components]] more "seamless".<ref name="reactjs.org-3" /> It is maintained by [[Meta Platforms|Meta]] (formerly Facebook) and a community of individual developers and companies.<ref>{{cite web |last=Krill |first=Paul |date=May 15, 2014 |title=React: Making faster, smoother UIs for data-driven Web apps |url=https://www.infoworld.com/article/2608181/javascript/react--making-faster--smoother-uis-for-data-driven-web-apps.html |access-date=2021-02-23 |website=[[InfoWorld]] |archive-date=2018-06-12 |archive-url=https://web.archive.org/web/20180612141516/https://www.infoworld.com/article/2608181/javascript/react--making-faster--smoother-uis-for-data-driven-web-apps.html |url-status=live }}</ref><ref>{{cite web |last=Hemel |first=Zef |date=June 3, 2013 |title=Facebook's React JavaScript User Interfaces Library Receives Mixed Reviews |url=https://www.infoq.com/news/2013/06/facebook-react |url-status=live |access-date=2022-01-11 |website=infoq.com |language=en-US |archive-url=https://web.archive.org/web/20220526082114/https://www.infoq.com/news/2013/06/facebook-react/ |archive-date=May 26, 2022}}</ref><ref>{{cite web |last=Dawson |first=Chris |date=July 25, 2014 |title=JavaScript's History and How it Led To ReactJS |url=https://thenewstack.io/javascripts-history-and-how-it-led-to-reactjs/ |url-status=live |access-date=2020-07-19 |website=The New Stack |language=en-US |archive-url=https://web.archive.org/web/20200806190027/https://thenewstack.io/javascripts-history-and-how-it-led-to-reactjs/ |archive-date=Aug 6, 2020 }}</ref>
React can be used to develop [[single-page application|single-page]], mobile, or [[server-side rendering|server-rendered]] applications with frameworks like [[Next.js]] and [[Remix (web framework)|Remix]]{{Efn|Merged into [[React Router]] since React Router v7<ref>{{Cite web |last=Lybrand |first=Brooks |date=2024-05-15 |title=Merging Remix and React Router |url=https://remix.run/blog/merging-remix-and-react-router |access-date=2024-12-25 |website=remix.run |language=en}}</ref>}}. Because React is only concerned with the user interface and rendering components to the [[Document Object Model|DOM]], React applications often rely on [[JavaScript libraries|libraries]] for routing and other client-side functionality.{{sfn|Dere|2017}}{{sfn|Panchal|2022}} A key advantage of React is that it only re-renders those parts of the page that have changed, avoiding unnecessary re-rendering of unchanged DOM elements.
== Notable features ==
=== Declarative ===
React adheres to the [[declarative programming]] [[Programming paradigm|paradigm]].<ref>{{Cite web |date=2017-09-27 |title=React Introduction |url=https://www.geeksforgeeks.org/reactjs-introduction/ |access-date=2024-10-12 |website=GeeksforGeeks |language=en-US}}</ref>
=== Components ===
React code is made of entities called [[Component-based software engineering|components]].{{sfn|Wieruch|2020}}{{rp|10-12}} These components are modular and
The two primary ways of declaring components in React are through function components and class components.{{sfn|Wieruch|2020}}{{rp|118}}{{sfn|Larsen|2021}}{{rp|10}} Since React v16.8, using function components is the recommended way.
=== Function components ===
Function components,
<ref name="introducing_hooks"/>
=== React Hooks ===
On February 16, 2019, React 16.8 was released to the public, introducing React Hooks.<ref name="introducing_hooks">{{cite web
|url=https://reactjs.org/docs/hooks-intro.html
|title=Introducing Hooks
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}}</ref> Hooks are functions that let developers "hook into" React state and lifecycle features from function components.<ref>{{Cite web|url=https://reactjs.org/docs/hooks-overview.html|title=Hooks at a Glance – React|website=reactjs.org|language=en|access-date=2019-08-08|archive-date=2023-03-15|archive-url=https://web.archive.org/web/20230315054047/https://reactjs.org/docs/hooks-overview.html|url-status=live}}</ref> Notably, Hooks do not work inside classes — they let developers use more features of React without classes.<ref>{{Cite web |date=2020-01-16 |title=What the Heck is React Hooks? |url=https://soshace.com/2020/01/16/what-the-heck-is-react-hooks/ |url-status=live |archive-url=https://web.archive.org/web/20220531133601/https://blog.soshace.com/what-the-heck-is-react-hooks/ |archive-date=2022-05-31 |access-date=2020-01-24 |website=Soshace |language=en}}</ref>
React provides several built-in hooks such as <code>useState</code>,<ref>{{Cite web|url=https://reactjs.org/docs/hooks-state.html|title=Using the State Hook – React|website=reactjs.org|language=en|access-date=2020-01-24|archive-date=2022-07-30|archive-url=https://web.archive.org/web/20220730180312/https://reactjs.org/docs/hooks-state.html|url-status=live}}</ref>{{sfn|Larsen|2021}}{{rp|37}} <code>useContext</code>,{{sfn|Wieruch|2020}}{{rp|11}}<ref name="reactjs.org-2">{{Cite web|url=https://reactjs.org/docs/hooks-state.html|title=Using the State Hook – React|website=reactjs.org|language=en|access-date=2020-01-24|archive-date=2022-07-30|archive-url=https://web.archive.org/web/20220730180312/https://reactjs.org/docs/hooks-state.html|url-status=live}}</ref>{{sfn|Larsen|2021}}{{rp|12}} <code>useReducer</code>,{{sfn|Wieruch|2020}}{{rp|92}}<ref name="reactjs.org-2" />{{sfn|Larsen|2021}}{{rp|65-66}} <code>useMemo</code>{{sfn|Wieruch|2020}}{{rp|154}}<ref name="reactjs.org-2" />{{sfn|Larsen|2021}}{{rp|162}} and <code>useEffect</code>.<ref>{{Cite web|url=https://reactjs.org/docs/hooks-effect.html|title=Using the Effect Hook – React|website=reactjs.org|language=en|access-date=2020-01-24|archive-date=2022-08-01|archive-url=https://web.archive.org/web/20220801212858/https://reactjs.org/docs/hooks-effect.html|url-status=live}}</ref>{{sfn|Larsen|2021}}{{rp|93-95}} Others are documented in the Hooks API Reference.<ref>{{Cite web|url=https://reactjs.org/docs/hooks-reference.html|title=Hooks API Reference – React|website=reactjs.org|language=en|access-date=2020-01-24|archive-date=2022-08-05|archive-url=https://web.archive.org/web/20220805061010/https://reactjs.org/docs/hooks-reference.html|url-status=live}}</ref>{{sfn|Wieruch|2020}}{{rp|62}} <code>useState</code> and <code>useEffect</code>, which are the most commonly used, are for controlling [[State (computer science)|state]]{{sfn|Wieruch|2020}}{{rp|37}} and [[Side effect (computer science)|side effects]],{{sfn|Wieruch|2020}}{{rp|61}} respectively.
==== Rules of hooks ====
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=== Server components ===
React server components (RSC) <ref>{{Cite web|url=https://react.dev/blog/2023/03/22/react-labs-what-we-have-been-working-on-march-2023#react-server-components|title=React Labs: What We've Been Working On – March 2023|website=react.dev|language=en|access-date=2023-07-23|archive-date=2023-07-26|archive-url=https://web.archive.org/web/20230726201006/https://react.dev/blog/2023/03/22/react-labs-what-we-have-been-working-on-march-2023#react-server-components|url-status=live}}</ref> are function components that run exclusively on the server. The concept was first introduced in the talk "Data Fetching with Server Components".<ref>{{Cite web |
<syntaxhighlight lang="jsx" line="1">
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</syntaxhighlight>
Currently, server components are most readily usable with [[Next.js]]. With Next.js, it's possible to write components for both the server and the client (browser). When a server rendered component is received by the browser, React in the browser takes over and creates the virtual DOM and attach event handlers. This is called hydration.
<ref>{{Cite web |title= hydrate |url=https://18.react.dev/reference/react-dom/hydrate#hydrating-server-rendered-html |access-date=2025-06-19 |language=en |archive-url=https://web.archive.org/web/20240716002720/https://18.react.dev/reference/react-dom/hydrate#hydrating-server-rendered-html |archive-date=2024-07-16 |url-status=live }}</ref>
=== Class components ===
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=== Virtual DOM ===
Another notable feature is the use of a virtual [[Document Object Model]], or [[Virtual DOM]]. React creates an [[In-memory processing|in-memory]] data-structure
==== Updates ====
When <code>ReactDOM.render</code><ref>{{Cite web |title=ReactDOM – React |url=https://reactjs.org/docs/react-dom.html |access-date=2023-01-08 |website=reactjs.org |language=en |archive-date=2023-01-08 |archive-url=https://web.archive.org/web/20230108104936/https://reactjs.org/docs/react-dom.html |url-status=live }}</ref> is called again for the same component and target, React represents the new UI state in the Virtual DOM and determines which parts (if any) of the living DOM needs to change.<ref>{{Cite web |title=Reconciliation – React |url=https://reactjs.org/docs/reconciliation.html |access-date=2023-01-08 |website=reactjs.org |language=en |archive-date=2023-01-08 |archive-url=https://web.archive.org/web/20230108105122/https://reactjs.org/docs/reconciliation.html |url-status=live }}</ref>
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=== JSX ===
{{Main|JSX (JavaScript)|l1=JSX}}
[[JSX (JavaScript)|JSX]], or JavaScript XML, is an extension to the JavaScript language syntax.<ref>{{cite web |date=2022-03-08 |title=Draft: JSX Specification |url=https://facebook.github.io/jsx/ |access-date=7 April 2018 |website=JSX |publisher=Facebook |language=en-US |archive-date=2022-04-02 |archive-url=https://web.archive.org/web/20220402072504/https://facebook.github.io/jsx/ |url-status=live }}</ref> Similar in appearance to HTML,{{sfn|Wieruch|2020}}{{rp|11}} JSX provides a way to structure component rendering using syntax familiar{{sfn|Wieruch|2020}}{{rp|15}} to many developers. React components are typically written using JSX, although they do not have to be (components may also be written in pure JavaScript). During compilation, JSX is converted to JavaScript code. JSX is similar to another extension syntax created by Facebook for [[PHP]] called [[XHP]].
An example of JSX code:
<syntaxhighlight lang="jsx">
function Example() {
// Declare a new state variable, which we'll call "count"
const [count, setCount] = useState(0);
return (▼
<div>▼
<button onClick={() => setCount(count + 1)}>
</div>▼
}▼
}
</syntaxhighlight>
=== Architecture beyond HTML ===
The basic [[Software architecture|architecture]] of React applies beyond rendering HTML in the browser. For example, Facebook has dynamic charts that render to <code><nowiki><canvas></nowiki></code> tags,<ref>{{cite web |last=Hunt |first=Pete |date=2013-06-05 |title=Why did we build React? – React Blog |url=https://facebook.github.io/react/blog/2013/06/05/why-react.html |access-date=2022-02-17 |website=reactjs.org |language=en-US |archive-date=2015-04-06 |archive-url=https://web.archive.org/web/20150406072833/http://facebook.github.io/react/blog/2013/06/05/why-react.html |url-status=dead }}</ref> and Netflix and [[PayPal]] use universal loading to render identical HTML on both the server and client.<ref name="medium.com-2015">{{cite web |date=2015-04-27 |title=PayPal Isomorphic React |url=https://medium.com/paypal-engineering/isomorphic-react-apps-with-react-engine-17dae662379c |url-status=live |archive-url=https://web.archive.org/web/20190208124143/https://www.paypal-engineering.com/2015/04/27/isomorphic-react-apps-with-react-engine/ |archive-date=2019-02-08 |access-date=2019-02-08 |website=medium.com}}</ref><ref name="netflixtechblog.com-2015">{{cite web |date=2015-01-28 |title=Netflix Isomorphic React |url=http://techblog.netflix.com/2015/01/netflix-likes-react.html |access-date=2022-02-14 |website=netflixtechblog.com |language=en-US |archive-date=2016-12-17 |archive-url=https://web.archive.org/web/20161217043150/http://techblog.netflix.com/2015/01/netflix-likes-react.html |url-status=live }}</ref> React can also be used to develop native apps for Android and iOS using [[React Native]].
=== Server-side rendering ===
[[Server-side scripting|Server-side rendering]] (SSR) refers to the process of rendering a client-side JavaScript application on the server, rather than in the browser.<ref
{{cite web
▲[[Server-side scripting|Server-side rendering]] (SSR) refers to the process of rendering a client-side JavaScript application on the server, rather than in the browser. This can improve the performance of the application, especially for users on slower connections or devices.
|title=Server-side rendering (SSR) - MDN Web Docs Glossary
|url=https://developer.mozilla.org/en-US/docs/Glossary/SSR
|website=MDN Web Docs
|publisher=Mozilla
|access-date=7 March 2025
}}
</ref> This can improve the performance of the application, especially for users on slower connections or devices.<ref name="GoogleRendering">
{{cite web
|title=Rendering on the Web
|url=https://web.dev/rendering-on-the-web/
|website=web.dev
|publisher=Google
|date=6 February 2019
|access-date=7 March 2025
}}
</ref>
With SSR, the initial HTML that is sent to the client includes the fully rendered UI of the application.<ref
{{cite web
|last=Jain
|first=Atishay
|title=Render Caching for React
|url=https://css-tricks.com/render-caching-for-react/
|website=CSS-Tricks
|date=10 November 2018
|access-date=7 March 2025
}}
</ref> This allows the client's browser to display the UI immediately, rather than having to wait for the JavaScript to download and execute before rendering the UI.<ref name="CSS-Tricks-SSR" />
React supports SSR, which allows developers to render React components on the server and send the resulting HTML to the client.<ref
{{cite web
|title=Server React DOM APIs
|url=https://react.dev/reference/react-dom/server
|website=React Documentation
|publisher=Meta Platforms
|access-date=7 March 2025
}}
</ref> This can be useful for improving the performance of the application, as well as for [[search engine optimization]] purposes.<ref name="NextDocs">
{{cite web
|title=Rendering (Next.js Documentation)
|url=https://nextjs.org/docs/pages/building-your-application/rendering
|website=Next.js Documentation
|publisher=Vercel
|access-date=7 March 2025
}}
</ref>
== Common idioms ==
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=== Unidirectional data flow ===
{{Main|Unidirectional data flow}}
To support React's concept of unidirectional data flow (which might be contrasted with [[AngularJS]]'s bidirectional flow), the ''Flux'' architecture was developed as an alternative to the popular [[model–view–controller]] architecture. Flux features ''actions'' which are sent through a central ''dispatcher'' to a ''store'', and changes to the store are propagated back to the view.<ref name="Flux">{{cite web|url=https://facebook.github.io/flux/docs/in-depth-overview|title=In Depth OverView|publisher=Facebook|access-date=7 April 2018|website=Flux|archive-date=7 August 2022|archive-url=https://web.archive.org/web/20220807201252/https://facebook.github.io/flux/docs/in-depth-overview/|url-status=dead}}</ref> When used with React, this propagation is accomplished through component properties. Since its conception, Flux has been superseded by libraries such as [[Redux (JavaScript library)|Redux]] and MobX.<ref>{{cite web|title=Flux Release 4.0|url=https://github.com/facebook/flux/releases/tag/4.0.0|website=Github|access-date=26 February 2021|archive-date=31 May 2022|archive-url=https://web.archive.org/web/20220531133558/https://github.com/facebook/flux/releases/tag/4.0.0|url-status=live}}</ref>
Flux can be considered a variant of the [[observer pattern]].<ref>{{cite web|last1=Johnson|first1=Nicholas|title=Introduction to Flux – React Exercise|url=http://nicholasjohnson.com/react/course/exercises/flux/|website=Nicholas Johnson|access-date=7 April 2018|archive-date=31 May 2022|archive-url=https://web.archive.org/web/20220531133600/http://nicholasjohnson.com/react/course/exercises/flux/|url-status=live}}</ref>
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This pattern is sometimes expressed as "properties flow down, actions flow up". Many implementations of Flux have been created since its inception, perhaps the most well-known being [[Redux (JavaScript library)|Redux]], which features a single store, often called a [[single source of truth]].<ref>{{cite web|title=State Management Tools – Results|url=http://2016.stateofjs.com/2016/statemanagement/|website=The State of JavaScript|access-date=29 October 2021|archive-date=31 May 2022|archive-url=https://web.archive.org/web/20220531133609/http://2016.stateofjs.com/2016/statemanagement/|url-status=live}}</ref>
In February 2019, <code>useReducer</code> was introduced as a [[
== History ==
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On September 26, 2017, React 16.0.0 was released with the MIT license.<ref>{{cite web |url=https://reactjs.org/blog/2017/09/26/react-v16.0.html#mit-licensed |title=React v16.0§MIT licensed |last=Clark |first=Andrew |date=September 26, 2017 |website=React Blog |access-date=October 18, 2017 |archive-date=October 3, 2017 |archive-url=https://web.archive.org/web/20171003031315/https://reactjs.org/blog/2017/09/26/react-v16.0.html#mit-licensed |url-status=live }}</ref> The MIT license change has also been backported to the 15.x release line with React 15.6.2.<ref>{{cite web |url=https://reactjs.org/blog/2017/09/25/react-v15.6.2.html |title=React v15.6.2 |last=Hunzaker |first=Nathan |date=September 25, 2017 |website=React Blog |access-date=October 18, 2017 |archive-date=May 31, 2022 |archive-url=https://web.archive.org/web/20220531133328/https://reactjs.org/blog/2017/09/25/react-v15.6.2.html |url-status=live }}</ref>
== Comparison with other frameworks ==
JavaScript-based web application frameworks, such as React, provide extensive capabilities but come with associated trade-offs. These frameworks often extend or enhance features available through native web technologies, such as routing, component-based development, and state management. While native web standards, including Web Components, modern JavaScript APIs like Fetch and ES Modules, and browser capabilities like Shadow DOM, have advanced significantly, frameworks remain widely used for their ability to enhance developer productivity, offer structured patterns for large-scale applications, simplify handling edge cases, and provide tools for performance optimization. <ref name=":02">{{Cite book |title=JavaScript Frameworks for Modern Web Development: The Essential Frameworks, Libraries, and Tools to Learn Right Now |isbn=978-1484249949 |last1=Uzayr |first1=Sufyan bin |last2=Cloud |first2=Nicholas |last3=Ambler |first3=Tim |date=November 2019 |publisher=Apress }}</ref><ref name=":12">{{Cite book |title=Building Native Web Components: Front-End Development with Polymer and Vue.js |isbn=978-1484259047}}</ref><ref name=":22">{{Cite book |title=Hands-On JavaScript High Performance: Build faster web apps using Node.js, Svelte.js, and WebAssembly |isbn=978-1838821098}}</ref>
Frameworks can introduce abstraction layers that may contribute to performance overhead, larger bundle sizes, and increased complexity. Modern frameworks, such as React 18, address these challenges with features like concurrent rendering, tree-shaking, and selective hydration. While these advancements improve rendering efficiency and resource management, their benefits depend on the specific application and implementation context. Lightweight frameworks, such as Svelte and Preact, take different architectural approaches, with Svelte eliminating the virtual DOM entirely in favor of compiling components to efficient JavaScript code, and Preact offering a minimal, compatible alternative to React. Framework choice depends on an application’s requirements, including the team’s expertise, performance goals, and development priorities. <ref name=":02" /><ref name=":12" /><ref name=":22" />
A newer category of web frameworks, including enhance.dev, Astro, and Fresh, leverages native web standards while minimizing abstractions and development tooling. <ref>{{Cite web |title=Enhance |website=[[GitHub]] |url=https://github.com/enhance-dev }}</ref><ref>{{Cite web |title=Astro framework |website=[[GitHub]] |url=https://github.com/withastro/astro }}</ref><ref>{{Cite web |title=Fresh |website=[[GitHub]] |url=https://github.com/denoland/fresh }}</ref> These solutions emphasize [[progressive enhancement]], [[server-side rendering]], and optimizing performance. Astro renders static HTML by default while hydrating only interactive parts. Fresh focuses on server-side rendering with zero runtime overhead. Enhance.dev prioritizes progressive enhancement patterns using Web Components. While these tools reduce reliance on client-side JavaScript by shifting logic to build-time or server-side execution, they still use JavaScript where necessary for interactivity. This approach makes them particularly suitable for performance-critical and content-focused applications. <ref name=":02" /><ref name=":12" /><ref name=":22" />
== See also ==
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* {{cite book |last1=Schwarzmüller |first1=Max |date=2018-05-01 |title=React – The Complete Guide (incl. Hooks, React Router and Redux) |publisher=[[Packt Publishing]] |language=en-US}}
* {{cite book |last=Wieruch |first=Robin |title=The Road to React |publisher=Leanpub |isbn=978-1-72004-399-7 |year=2020}}
* {{cite news |last=Dere |first=Mohan |date=2017-12-21 |title=How to integrate create-react-app with all the libraries you need to make a great app |language=en-US |work=freeCodeCamp |url=https://
* {{cite news |last=Panchal |first=Krunal |date=2022-04-26 |title=Angular vs React Detailed Comparison |language=en-US |work=SitePoint |url=https://www.sitepoint.com/angular-vs-react/ |access-date=2023-06-05 |archive-date=2023-03-30 |archive-url=https://web.archive.org/web/20230330160838/https://www.sitepoint.com/angular-vs-react/ |url-status=live }}
* {{cite news |last1=Hámori |first1=Fenerec |title=The History of React.js on a Timeline |url=https://blog.risingstack.com/the-history-of-react-js-on-a-timeline/ |access-date=2023-06-05 |work=RisingStack |date=2022-05-31 |archive-date=2022-05-31 |archive-url=https://web.archive.org/web/20220531133616/https://blog.risingstack.com/the-history-of-react-js-on-a-timeline/ |url-status=live }}
| |||