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Paul O’Shannessy
230 lines
12 KiB
HTML
230 lines
12 KiB
HTML
<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
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<title>React | Advanced Components</title>
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<meta name="viewport" content="width=device-width">
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<meta property="og:title" content="React | Advanced Components" />
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<meta property="og:type" content="website" />
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<meta property="og:url" content="http://facebook.github.io/react/docs/advanced-components.html" />
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<meta property="og:image" content="http://facebook.github.io/react/img/logo_og.png" />
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<meta property="og:description" content="A JavaScript library for building user interfaces" />
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<link rel="shortcut icon" href="/react/favicon.ico">
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<link rel="stylesheet" href="/react/css/react.css">
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<link rel="stylesheet" href="/react/css/syntax.css">
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<script type="text/javascript" src="//use.typekit.net/vqa1hcx.js"></script>
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<script type="text/javascript">try{Typekit.load();}catch(e){}</script>
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<script type="text/javascript" src="/react/js/codemirror.js"></script>
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<script type="text/javascript" src="/react/js/javascript.js"></script>
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<script type="text/javascript" src="/react/js/react.min.js"></script>
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<script type="text/javascript" src="/react/js/JSXTransformer.js"></script>
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<script type="text/javascript" src="/react/js/live_editor.js"></script>
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<script type="text/javascript" src="/react/js/showdown.js"></script>
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</head>
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<body>
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<div class="container">
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<div class="nav-main">
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<div class="wrap">
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<a class="nav-home" href="/react/index.html">
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<img class="nav-logo" alt="" src="/react/img/logo_small.png">
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React
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</a>
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<ul class="nav-site">
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<li><a href="/react/docs/getting-started.html" class="active">docs</a></li>
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<li><a href="/react/support.html">support</a></li>
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<li><a href="/react/downloads.html">download</a></li>
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<li><a href="/react/blog/">blog</a></li>
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<li><a href="http://github.com/facebook/react">github</a>
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</ul>
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<!-- <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> -->
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</div>
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</div>
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<section class="content wrap documentationContent">
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<div class="nav-docs">
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<div class="nav-docs-section">
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<h3>Getting started</h3>
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<ul>
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<li><a href="/react/docs/getting-started.html">Getting Started</a></li>
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<li><a href="/react/docs/tutorial.html">Tutorial</a></li>
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<li><a href="/react/docs/common-questions.html">Common Questions</a></li>
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</ul>
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</div>
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<div class="nav-docs-section">
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<h3>Reference</h3>
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<ul>
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<li><a href="/react/docs/syntax.html">JSX Syntax</a></li>
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<li><a href="/react/docs/component-basics.html">Component Basics</a></li>
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<li><a href="/react/docs/component-data.html">Component Data</a></li>
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<li><a href="/react/docs/component-lifecycle.html">Component Lifecycle</a></li>
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<li><a href="/react/docs/event-handling.html">Event Handling</a></li>
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<li><a href="/react/docs/advanced-components.html" class="active">Advanced Components</a></li>
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<li><a href="/react/docs/mixins.html">Mixins</a></li>
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<li><a href="/react/docs/api.html">API</a></li>
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</ul>
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</div>
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</div>
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<div class="inner-content">
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<h1>Advanced Components</h1>
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<div class="subHeader">How to build advanced composite components.</div>
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<p>Composite components extend a <code>ReactCompositeComponent</code> base class that provides
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a very powerful API that makes React flexible and able to easily work with other
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libraries and frameworks.</p>
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<h2>Lifecycle Methods</h2>
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<p>Composite components can optionally implement lifecycle methods that are invoked
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at various stages in the <a href="component-lifecycle.html">component lifecycle</a> that
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each have unique guarantees.</p>
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<h3>Mounting</h3>
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<ul>
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<li><code>getInitialState(): object</code> is invoked before a component is mounted.
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Stateful components should implement this and return the initial state data.</li>
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<li><code>componentWillMount()</code> is invoked immediately before mounting occurs.</li>
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<li><code>componentDidMount(DOMElement rootNode)</code> is invoked immediately after
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mounting occurs. Initialization that requires DOM nodes should go here.</li>
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</ul>
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<h3>Updating</h3>
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<ul>
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<li><code>componentWillReceiveProps(object nextProps)</code> is invoked when a mounted
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component receives new props. This method should be used to compare
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<code>this.props</code> and <code>nextProps</code> to perform state transitions using
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<code>this.setState()</code>.</li>
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<li><code>shouldComponentUpdate(object nextProps, object nextState): boolean</code> is
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invoked when a component decides whether any changes warrant an update to the
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DOM. Implement this as an optimization to compare <code>this.props</code> with
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<code>nextProps</code> and <code>this.state</code> with <code>nextState</code> and return false if React
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should skip updating.</li>
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<li><code>componentWillUpdate(object nextProps, object nextState)</code> is invoked
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immediately before updating occurs. You cannot call <code>this.setState()</code> here.</li>
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<li><code>componentDidUpdate(object prevProps, object prevState, DOMElement rootNode)</code>
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is invoked immediately after updating occurs.</li>
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</ul>
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<h3>Unmounting</h3>
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<ul>
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<li><code>componentWillUnmount()</code> is invoked immediately before a component is
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unmounted and destroyed. Cleanup should go here.</li>
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</ul>
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<h2>Mounted Methods</h2>
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<p><em>Mounted</em> composite components also support the following methods:</p>
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<ul>
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<li><code>getDOMNode(): DOMElement</code> can be invoked on any mounted component in order
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to obtain a reference to its rendered DOM node.</li>
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<li><code>forceUpdate()</code> can be invoked on any mounted component when you know that
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some deeper aspect of the component's state has changed without using
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<code>this.setState()</code>.</li>
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</ul>
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<blockquote>
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<p>Note:</p>
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<p>The <code>DOMElement rootNode</code> argument of <code>componentDidMount()</code> and
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<code>componentDidUpdate()</code> is a convenience. The same node can be obtained by
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calling <code>this.getDOMNode()</code>.</p>
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</blockquote>
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<h2>Component Refs</h2>
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<p>A common use case of event callbacks or the lifecycle methods is to operate on a
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component returned by <code>render()</code>. For example, consider a search component that
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should auto-focus the input once mounted:</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">SearchForm</span> <span class="o">=</span> <span class="nx">React</span><span class="p">.</span><span class="nx">createClass</span><span class="p">({</span>
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<span class="nx">render</span><span class="o">:</span> <span class="kd">function</span><span class="p">()</span> <span class="p">{</span>
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<span class="k">return</span> <span class="p">(</span>
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<span class="o"><</span><span class="nx">form</span> <span class="nx">action</span><span class="o">=</span><span class="p">{</span><span class="k">this</span><span class="p">.</span><span class="nx">props</span><span class="p">.</span><span class="nx">action</span><span class="p">}</span><span class="o">></span>
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<span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"search"</span> <span class="nx">placeholder</span><span class="o">=</span><span class="s2">"Search..."</span> <span class="o">/></span>
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<span class="o"><</span><span class="err">/form></span>
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<span class="p">);</span>
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<span class="p">},</span>
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<span class="nx">componentDidMount</span><span class="o">:</span> <span class="kd">function</span><span class="p">(</span><span class="nx">rootNode</span><span class="p">)</span> <span class="p">{</span>
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<span class="kd">var</span> <span class="nx">searchInput</span> <span class="o">=</span> <span class="nx">rootNode</span><span class="p">.</span><span class="nx">firstChild</span><span class="p">;</span>
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<span class="nx">searchInput</span><span class="p">.</span><span class="nx">focus</span><span class="p">();</span>
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<span class="p">}</span>
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<span class="p">});</span>
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</code></pre></div>
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<p>Although this implementation works, it is fragile because <code>componentDidMount()</code>
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now relies on <code>render()</code> returning a particular DOM structure.</p>
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<p>React provides a better way for composite components to reference components
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that it constructs in its <code>render()</code> method through the use of refs. A component
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can assign a <code>ref</code> to any component it constructs. This will create a reference
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to those components on <code>this.refs</code>. For example:</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="kd">var</span> <span class="nx">SearchForm</span> <span class="o">=</span> <span class="nx">React</span><span class="p">.</span><span class="nx">createClass</span><span class="p">({</span>
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<span class="nx">render</span><span class="o">:</span> <span class="kd">function</span><span class="p">()</span> <span class="p">{</span>
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<span class="k">return</span> <span class="p">(</span>
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<span class="o"><</span><span class="nx">form</span> <span class="nx">action</span><span class="o">=</span><span class="p">{</span><span class="k">this</span><span class="p">.</span><span class="nx">props</span><span class="p">.</span><span class="nx">action</span><span class="p">}</span><span class="o">></span>
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<span class="hll"> <span class="o"><</span><span class="nx">input</span> <span class="nx">type</span><span class="o">=</span><span class="s2">"search"</span> <span class="nx">placeholder</span><span class="o">=</span><span class="s2">"Search..."</span> <span class="nx">ref</span><span class="o">=</span><span class="s2">"searchInput"</span> <span class="o">/></span>
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</span> <span class="o"><</span><span class="err">/form></span>
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<span class="p">);</span>
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<span class="p">},</span>
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<span class="nx">componentDidMount</span><span class="o">:</span> <span class="kd">function</span><span class="p">(</span><span class="nx">rootNode</span><span class="p">)</span> <span class="p">{</span>
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<span class="hll"> <span class="kd">var</span> <span class="nx">searchInput</span> <span class="o">=</span> <span class="k">this</span><span class="p">.</span><span class="nx">refs</span><span class="p">.</span><span class="nx">searchInput</span><span class="p">.</span><span class="nx">getDOMNode</span><span class="p">();</span>
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</span> <span class="nx">searchInput</span><span class="p">.</span><span class="nx">focus</span><span class="p">();</span>
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<span class="p">}</span>
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<span class="p">});</span>
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</code></pre></div>
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<p>In this example, <code>this.refs.searchInput</code> will reference the <code><input></code> component
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and is available in most lifecycle methods and event callbacks. We obtain a
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reference to the <code><input></code>'s DOM node using <code>getDOMNode()</code>.</p>
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<blockquote>
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<p>Note:</p>
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<p>If you want to preserve compatibility with Google Closure Compiler's
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property crushing in <code>ADVANCED_OPTIMIZATIONS</code> mode, make sure to use string
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literals with <code>this.refs</code>.</p>
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</blockquote>
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<div class="docs-prevnext">
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<a class="docs-prev" href="/react/docs/event-handling.html">← Prev</a>
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