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<h1>
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Shallow Compare
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</h1>
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<div class="subHeader"></div>
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<p><code>shallowCompare</code> is a helper function to achieve the same functionality as <code>PureRenderMixin</code> while using ES6 classes with React.</p>
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<p>If your React component's render function is "pure" (in other words, it renders the same result given the same props and state), you can use this helper function for a performance boost in some cases.</p>
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<p>Example:</p>
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<div class="highlight"><pre><code class="language-js" data-lang="js"><span class="kd">var</span> <span class="nx">shallowCompare</span> <span class="o">=</span> <span class="nx">require</span><span class="p">(</span><span class="s1">'react-addons-shallow-compare'</span><span class="p">);</span>
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<span class="kr">export</span> <span class="kr">class</span> <span class="nx">SampleComponent</span> <span class="kr">extends</span> <span class="nx">React</span><span class="p">.</span><span class="nx">Component</span> <span class="p">{</span>
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<span class="nx">shouldComponentUpdate</span><span class="p">(</span><span class="nx">nextProps</span><span class="p">,</span> <span class="nx">nextState</span><span class="p">)</span> <span class="p">{</span>
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<span class="k">return</span> <span class="nx">shallowCompare</span><span class="p">(</span><span class="k">this</span><span class="p">,</span> <span class="nx">nextProps</span><span class="p">,</span> <span class="nx">nextState</span><span class="p">);</span>
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<span class="p">}</span>
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<span class="nx">render</span><span class="p">()</span> <span class="p">{</span>
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<span class="k">return</span> <span class="o"><</span><span class="nx">div</span> <span class="nx">className</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">className</span><span class="p">}</span><span class="o">></span><span class="nx">foo</span><span class="o"><</span><span class="err">/div>;</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><code>shallowCompare</code> performs a shallow equality check on the current <code>props</code> and <code>nextProps</code> objects as well as the current <code>state</code> and <code>nextState</code> objects.<br>
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It does this by iterating on the keys of the objects being compared and returning true when the values of a key in each object are not strictly equal.</p>
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<p><code>shallowCompare</code> returns <code>true</code> if the shallow comparison for props or state fails and therefore the component should update.<br>
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<code>shallowCompare</code> returns <code>false</code> if the shallow comparison for props and state both pass and therefore the component does not need to update.</p>
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if (d.getElementById(id)) return;
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js = d.createElement(s); js.id = id;
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js.src = "//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.6&appId=623268441017527";
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fjs.parentNode.insertBefore(js, fjs);
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}(document, 'script', 'facebook-jssdk'));
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docsearch({
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apiKey: '36221914cce388c46d0420343e0bb32e',
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indexName: 'react',
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inputSelector: '#algolia-doc-search'
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});
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</script>
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</body>
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</html>
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