mirror of
https://github.com/facebook/react.git
synced 2025-11-01 09:12:30 +00:00
415 lines
21 KiB
HTML
415 lines
21 KiB
HTML
<!DOCTYPE html>
|
|
<html>
|
|
<head>
|
|
<meta charset="utf-8">
|
|
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
|
|
<title>React | JSX in Depth</title>
|
|
<meta name="viewport" content="width=device-width">
|
|
<meta property="og:title" content="React | JSX in Depth" />
|
|
<meta property="og:type" content="website" />
|
|
<meta property="og:url" content="http://facebook.github.io/react/docs/jsx-in-depth.html" />
|
|
<meta property="og:image" content="http://facebook.github.io/react/img/logo_og.png" />
|
|
<meta property="og:description" content="A JavaScript library for building user interfaces" />
|
|
<meta property="fb:app_id" content="623268441017527" />
|
|
|
|
<link rel="shortcut icon" href="/react/favicon.ico">
|
|
<link rel="alternate" type="application/rss+xml" title="React" href="http://facebook.github.io/react/feed.xml">
|
|
|
|
<link rel="stylesheet" href="/react/css/react.css">
|
|
<link rel="stylesheet" href="/react/css/syntax.css">
|
|
<link rel="stylesheet" href="/react/css/codemirror.css">
|
|
|
|
<script type="text/javascript" src="//use.typekit.net/vqa1hcx.js"></script>
|
|
<script type="text/javascript">try{Typekit.load();}catch(e){}</script>
|
|
|
|
<script type="text/javascript" src="/react/js/codemirror.js"></script>
|
|
<script type="text/javascript" src="/react/js/javascript.js"></script>
|
|
<script type="text/javascript" src="/react/js/react.min.js"></script>
|
|
<script type="text/javascript" src="/react/js/JSXTransformer.js"></script>
|
|
<script type="text/javascript" src="/react/js/live_editor.js"></script>
|
|
<script type="text/javascript" src="/react/js/showdown.js"></script>
|
|
</head>
|
|
<body>
|
|
|
|
<div class="container">
|
|
|
|
<div class="nav-main">
|
|
<div class="wrap">
|
|
<a class="nav-home" href="/react/index.html">
|
|
<img class="nav-logo" alt="" src="/react/img/logo_small.png" width="38" height="38">
|
|
React
|
|
</a>
|
|
<ul class="nav-site">
|
|
<li><a href="/react/docs/getting-started.html" class="active">docs</a></li>
|
|
<li><a href="/react/support.html">support</a></li>
|
|
<li><a href="/react/downloads.html">download</a></li>
|
|
<li><a href="/react/blog/">blog</a></li>
|
|
<li><a href="http://github.com/facebook/react">github</a>
|
|
</ul>
|
|
<!-- <iframe src="http://ghbtns.com/github-btn.html?user=facebook&repo=react.js&type=fork"allowtransparency="true" frameborder="0" scrolling="0" width="62" height="20"></iframe> -->
|
|
</div>
|
|
</div>
|
|
|
|
|
|
|
|
<section class="content wrap documentationContent">
|
|
<div class="nav-docs">
|
|
|
|
<div class="nav-docs-section">
|
|
<h3>Quick Start</h3>
|
|
<ul>
|
|
|
|
<li>
|
|
<a href="/react/docs/getting-started.html">
|
|
Getting Started
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/tutorial.html">
|
|
Tutorial
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</div>
|
|
|
|
<div class="nav-docs-section">
|
|
<h3>Guides</h3>
|
|
<ul>
|
|
|
|
<li>
|
|
<a href="/react/docs/why-react.html">
|
|
Why React?
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/displaying-data.html">
|
|
Displaying Data
|
|
</a>
|
|
|
|
<ul>
|
|
|
|
<li>
|
|
<a href="/react/docs/jsx-in-depth.html" class="active">
|
|
JSX in Depth
|
|
</a>
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/jsx-gotchas.html">
|
|
JSX Gotchas
|
|
</a>
|
|
</li>
|
|
|
|
</ul>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/interactivity-and-dynamic-uis.html">
|
|
Interactivity and Dynamic UIs
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/multiple-components.html">
|
|
Multiple Components
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/reusable-components.html">
|
|
Reusable Components
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/forms.html">
|
|
Forms
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/working-with-the-browser.html">
|
|
Working With the Browser
|
|
</a>
|
|
|
|
<ul>
|
|
|
|
<li>
|
|
<a href="/react/docs/more-about-refs.html">
|
|
More About Refs
|
|
</a>
|
|
</li>
|
|
|
|
</ul>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/tooling-integration.html">
|
|
Tooling Integration
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/addons.html">
|
|
Add-ons
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/examples.html">
|
|
Examples
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</div>
|
|
|
|
<div class="nav-docs-section">
|
|
<h3>Reference</h3>
|
|
<ul>
|
|
|
|
<li>
|
|
<a href="/react/docs/top-level-api.html">
|
|
Top-Level API
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/component-api.html">
|
|
Component API
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/component-specs.html">
|
|
Component Specs and Lifecycle
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/tags-and-attributes.html">
|
|
Supported Tags and Attributes
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/events.html">
|
|
Event System
|
|
</a>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
<a href="/react/docs/dom-differences.html">
|
|
DOM Differences
|
|
</a>
|
|
|
|
</li>
|
|
|
|
</ul>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
|
|
<div class="inner-content">
|
|
<h1>JSX in Depth</h1>
|
|
<div class="subHeader"></div>
|
|
<p>JSX is a JavaScript XML syntax transform recommended for use
|
|
with React.</p>
|
|
<h2 id="why-jsx"><a href="#why-jsx">Why JSX?</a></h2>
|
|
<p>React works out of the box without JSX. Simply construct your markup using the
|
|
functions on <code>React.DOM</code>. For example, here's how to construct a simple link:</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">link</span> <span class="o">=</span> <span class="nx">React</span><span class="p">.</span><span class="nx">DOM</span><span class="p">.</span><span class="nx">a</span><span class="p">({</span><span class="nx">href</span><span class="o">:</span> <span class="s1">'http://facebook.github.io/react'</span><span class="p">},</span> <span class="s1">'React'</span><span class="p">);</span>
|
|
</code></pre></div>
|
|
<p>We recommend using JSX for many reasons:</p>
|
|
|
|
<ul>
|
|
<li>It's easier to visualize the structure of the DOM.</li>
|
|
<li>Designers are more comfortable making changes.</li>
|
|
<li>It's familiar for those who have used MXML or XAML.</li>
|
|
</ul>
|
|
<h2 id="the-transform"><a href="#the-transform">The Transform</a></h2>
|
|
<p>JSX transforms from an XML-like syntax into native JavaScript. XML elements and
|
|
attributes are transformed into function calls and objects, respectively.</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">Nav</span><span class="p">;</span>
|
|
<span class="c1">// Input (JSX):</span>
|
|
<span class="kd">var</span> <span class="nx">app</span> <span class="o">=</span> <span class="o"><</span><span class="nx">Nav</span> <span class="nx">color</span><span class="o">=</span><span class="s2">"blue"</span> <span class="o">/></span><span class="p">;</span>
|
|
<span class="c1">// Output (JS):</span>
|
|
<span class="kd">var</span> <span class="nx">app</span> <span class="o">=</span> <span class="nx">Nav</span><span class="p">({</span><span class="nx">color</span><span class="o">:</span><span class="s2">"blue"</span><span class="p">});</span>
|
|
</code></pre></div>
|
|
<p>Notice that in order to use <code><Nav /></code>, the <code>Nav</code> variable must be in scope.</p>
|
|
|
|
<p>JSX also allows specifying children using XML syntax:</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">Nav</span><span class="p">,</span> <span class="nx">Profile</span><span class="p">;</span>
|
|
<span class="c1">// Input (JSX):</span>
|
|
<span class="kd">var</span> <span class="nx">app</span> <span class="o">=</span> <span class="o"><</span><span class="nx">Nav</span> <span class="nx">color</span><span class="o">=</span><span class="s2">"blue"</span><span class="o">><</span><span class="nx">Profile</span><span class="o">></span><span class="nx">click</span><span class="o"><</span><span class="err">/Profile></Nav>;</span>
|
|
<span class="c1">// Output (JS):</span>
|
|
<span class="kd">var</span> <span class="nx">app</span> <span class="o">=</span> <span class="nx">Nav</span><span class="p">({</span><span class="nx">color</span><span class="o">:</span><span class="s2">"blue"</span><span class="p">},</span> <span class="nx">Profile</span><span class="p">(</span><span class="kc">null</span><span class="p">,</span> <span class="s2">"click"</span><span class="p">));</span>
|
|
</code></pre></div>
|
|
<p>Use the <a href="/react/jsx-compiler.html">JSX Compiler</a> to try out JSX and see how it
|
|
desugars into native JavaScript.</p>
|
|
|
|
<p>If you want to use JSX, the <a href="getting-started.html">Getting Started</a> guide shows
|
|
how to setup compilation.</p>
|
|
|
|
<blockquote>
|
|
<p>Note:</p>
|
|
|
|
<p>Details about the code transform are given here to increase understanding, but
|
|
your code should not rely on these implementation details.</p>
|
|
</blockquote>
|
|
<h2 id="react-and-jsx"><a href="#react-and-jsx">React and JSX</a></h2>
|
|
<p>React and JSX are independent technologies, but JSX was primarily built with
|
|
React in mind. The two valid uses of JSX are:</p>
|
|
|
|
<ul>
|
|
<li>To construct instances of React DOM components (<code>React.DOM.*</code>).</li>
|
|
<li>To construct instances of composite components created with
|
|
<code>React.createClass()</code>.</li>
|
|
</ul>
|
|
<h3 id="react-dom-components"><a href="#react-dom-components">React DOM Components</a></h3>
|
|
<p>To construct a <code><div></code> is to create a variable that refers to <code>React.DOM.div</code>.</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">div</span> <span class="o">=</span> <span class="nx">React</span><span class="p">.</span><span class="nx">DOM</span><span class="p">.</span><span class="nx">div</span><span class="p">;</span>
|
|
<span class="kd">var</span> <span class="nx">app</span> <span class="o">=</span> <span class="o"><</span><span class="nx">div</span> <span class="nx">className</span><span class="o">=</span><span class="s2">"appClass"</span><span class="o">></span><span class="nx">Hello</span><span class="p">,</span> <span class="nx">React</span><span class="o">!<</span><span class="err">/div>;</span>
|
|
</code></pre></div><h3 id="react-composite-components"><a href="#react-composite-components">React Composite Components</a></h3>
|
|
<p>To construct an instance of a composite component, create a variable that
|
|
references the class.</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">MyComponent</span> <span class="o">=</span> <span class="nx">React</span><span class="p">.</span><span class="nx">createClass</span><span class="p">({</span><span class="cm">/*...*/</span><span class="p">});</span>
|
|
<span class="kd">var</span> <span class="nx">app</span> <span class="o">=</span> <span class="o"><</span><span class="nx">MyComponent</span> <span class="nx">someProperty</span><span class="o">=</span><span class="p">{</span><span class="kc">true</span><span class="p">}</span> <span class="o">/></span><span class="p">;</span>
|
|
</code></pre></div>
|
|
<p>See <a href="multiple-components.html">Multiple Components</a> to learn more about using composite components.</p>
|
|
|
|
<blockquote>
|
|
<p>Note:</p>
|
|
|
|
<p>Since JSX is JavaScript, identifiers such as <code>class</code> and <code>for</code> are discouraged
|
|
as XML attribute names. Instead, React DOM components expect attributes like
|
|
<code>className</code> and <code>htmlFor</code>, respectively.</p>
|
|
</blockquote>
|
|
<h2 id="dom-convenience"><a href="#dom-convenience">DOM Convenience</a></h2>
|
|
<p>Having to define variables for every type of DOM element can get tedious
|
|
(e.g. <code>var div, span, h1, h2, ...</code>). JSX provides a convenience to address this
|
|
problem by allowing you to specify a variable in an <code>@jsx</code> docblock field. JSX
|
|
will use that field to find DOM components.</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="cm">/**</span>
|
|
<span class="cm"> * @jsx React.DOM</span>
|
|
<span class="cm"> */</span>
|
|
<span class="kd">var</span> <span class="nx">Nav</span><span class="p">;</span>
|
|
<span class="c1">// Input (JSX):</span>
|
|
<span class="kd">var</span> <span class="nx">tree</span> <span class="o">=</span> <span class="o"><</span><span class="nx">Nav</span><span class="o">><</span><span class="nx">span</span> <span class="o">/><</span><span class="err">/Nav>;</span>
|
|
<span class="c1">// Output (JS):</span>
|
|
<span class="kd">var</span> <span class="nx">tree</span> <span class="o">=</span> <span class="nx">Nav</span><span class="p">(</span><span class="kc">null</span><span class="p">,</span> <span class="nx">React</span><span class="p">.</span><span class="nx">DOM</span><span class="p">.</span><span class="nx">span</span><span class="p">(</span><span class="kc">null</span><span class="p">));</span>
|
|
</code></pre></div>
|
|
<blockquote>
|
|
<p>Remember:</p>
|
|
|
|
<p>JSX simply transforms elements into function calls and has no notion of the
|
|
DOM. The docblock parameter is only a convenience to resolve the most commonly
|
|
used elements. In general, JSX has no notion of the DOM.</p>
|
|
</blockquote>
|
|
<h2 id="javascript-expressions"><a href="#javascript-expressions">JavaScript Expressions</a></h2><h3 id="attribute-expressions"><a href="#attribute-expressions">Attribute Expressions</a></h3>
|
|
<p>To use a JavaScript expression as an attribute value, wrap the expression in a
|
|
pair of curly braces (<code>{}</code>) instead of quotes (<code>""</code>).</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="c1">// Input (JSX):</span>
|
|
<span class="kd">var</span> <span class="nx">person</span> <span class="o">=</span> <span class="o"><</span><span class="nx">Person</span> <span class="nx">name</span><span class="o">=</span><span class="p">{</span><span class="nb">window</span><span class="p">.</span><span class="nx">isLoggedIn</span> <span class="o">?</span> <span class="nb">window</span><span class="p">.</span><span class="nx">name</span> <span class="o">:</span> <span class="s1">''</span><span class="p">}</span> <span class="o">/></span><span class="p">;</span>
|
|
<span class="c1">// Output (JS):</span>
|
|
<span class="kd">var</span> <span class="nx">person</span> <span class="o">=</span> <span class="nx">Person</span><span class="p">({</span><span class="nx">name</span><span class="o">:</span> <span class="nb">window</span><span class="p">.</span><span class="nx">isLoggedIn</span> <span class="o">?</span> <span class="nb">window</span><span class="p">.</span><span class="nx">name</span> <span class="o">:</span> <span class="s1">''</span><span class="p">});</span>
|
|
</code></pre></div><h3 id="child-expressions"><a href="#child-expressions">Child Expressions</a></h3>
|
|
<p>Likewise, JavaScript expressions may be used to express children:</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="c1">// Input (JSX):</span>
|
|
<span class="kd">var</span> <span class="nx">content</span> <span class="o">=</span> <span class="o"><</span><span class="nx">Container</span><span class="o">></span><span class="p">{</span><span class="nb">window</span><span class="p">.</span><span class="nx">isLoggedIn</span> <span class="o">?</span> <span class="o"><</span><span class="nx">Nav</span> <span class="o">/></span> <span class="o">:</span> <span class="o"><</span><span class="nx">Login</span> <span class="o">/></span><span class="p">}</span><span class="o"><</span><span class="err">/Container>;</span>
|
|
<span class="c1">// Output (JS):</span>
|
|
<span class="kd">var</span> <span class="nx">content</span> <span class="o">=</span> <span class="nx">Container</span><span class="p">(</span><span class="kc">null</span><span class="p">,</span> <span class="nb">window</span><span class="p">.</span><span class="nx">isLoggedIn</span> <span class="o">?</span> <span class="nx">Nav</span><span class="p">(</span><span class="kc">null</span><span class="p">)</span> <span class="o">:</span> <span class="nx">Login</span><span class="p">(</span><span class="kc">null</span><span class="p">));</span>
|
|
</code></pre></div><h3 id="comments"><a href="#comments">Comments</a></h3>
|
|
<p>It's easy to add comments within your JSX; they're just JS expressions:</p>
|
|
<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">content</span> <span class="o">=</span> <span class="o"><</span><span class="nx">Container</span><span class="o">></span><span class="p">{</span><span class="cm">/* this is a comment */</span><span class="p">}</span><span class="o"><</span><span class="nx">Nav</span> <span class="o">/><</span><span class="err">/Container>;</span>
|
|
</code></pre></div><h2 id="tooling"><a href="#tooling">Tooling</a></h2>
|
|
<p>Beyond the compilation step, JSX does not require any special tools.</p>
|
|
|
|
<ul>
|
|
<li>Many editors already include reasonable support for JSX (Vim, Emacs js2-mode).
|
|
|
|
<ul>
|
|
<li>JSX syntax highlighting is available for Sublime Text and other editors
|
|
that support <code>*.tmLanguage</code> using the third-party
|
|
<a href="https://github.com/yungsters/sublime/blob/master/tmLanguage/JavaScript%20(JSX).tmLanguage"><code>JavaScript (JSX).tmLanguage</code></a>.</li>
|
|
</ul></li>
|
|
<li>Linting provides accurate line numbers after compiling without sourcemaps.</li>
|
|
<li>Elements use standard scoping so linters can find usage of out-of-scope
|
|
components.</li>
|
|
</ul>
|
|
<h2 id="prior-work"><a href="#prior-work">Prior Work</a></h2>
|
|
<p>JSX is similar to several other JavaScript embedded XML language
|
|
proposals/projects. Some of the features of JSX that distinguish it from similar
|
|
efforts include:</p>
|
|
|
|
<ul>
|
|
<li>JSX is a simple syntactic transform.</li>
|
|
<li>JSX neither provides nor requires a runtime library.</li>
|
|
<li>JSX does not alter or add to the semantics of JavaScript.</li>
|
|
</ul>
|
|
|
|
<p>JSX is similar to HTML, but not exactly the same. See <a href="./jsx-gotchas.html">JSX gotchas</a> for some key differences.</p>
|
|
|
|
|
|
<div class="docs-prevnext">
|
|
|
|
<a class="docs-prev" href="/react/docs/displaying-data.html">← Prev</a>
|
|
|
|
|
|
<a class="docs-next" href="/react/docs/jsx-gotchas.html">Next →</a>
|
|
|
|
</div>
|
|
|
|
<div class="fb-comments" data-width="650" data-num-posts="10" data-href="http://facebook.github.io/react/docs/jsx-in-depth.html"></div>
|
|
</div>
|
|
</section>
|
|
|
|
|
|
<footer class="wrap">
|
|
<div class="left">A Facebook & Instagram collaboration.</div>
|
|
<div class="right">© 2013 Facebook Inc.</div>
|
|
</footer>
|
|
</div>
|
|
<div id="fb-root"></div>
|
|
<script>
|
|
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
|
|
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
|
|
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
|
|
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
|
|
ga('create', 'UA-41298772-1', 'facebook.github.io');
|
|
ga('send', 'pageview');
|
|
|
|
!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="https://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");
|
|
|
|
(function(d, s, id) {
|
|
var js, fjs = d.getElementsByTagName(s)[0];
|
|
if (d.getElementById(id)) return;
|
|
js = d.createElement(s); js.id = id;
|
|
js.src = "//connect.facebook.net/en_US/all.js#xfbml=1&appId=623268441017527";
|
|
fjs.parentNode.insertBefore(js, fjs);
|
|
}(document, 'script', 'facebook-jssdk'));
|
|
</script>
|
|
</body>
|
|
</html>
|