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<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>BackHandler · React Native</title><meta name="viewport" content="width=device-width"/><meta name="generator" content="Docusaurus"/><meta name="description" content="&lt;p&gt;Detect hardware button presses for back navigation.&lt;/p&gt;
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</script></nav></div><div class="container mainContainer"><div class="wrapper"><div class="post"><header class="postHeader"><a class="edit-page-link button" href="https://github.com/facebook/react-native-website/blob/master/docs/backhandler.md" target="_blank" rel="noreferrer noopener">Edit</a><h1 class="postHeaderTitle">BackHandler</h1></header><article><div><span><p>Detect hardware button presses for back navigation.</p>
<p>Android: Detect hardware back button presses, and programmatically invoke the default back button functionality to exit the app if there are no listeners or if none of the listeners return true.</p>
<p>tvOS: Detect presses of the menu button on the TV remote. (Still to be implemented: programmatically disable menu button handling functionality to exit the app if there are no listeners or if none of the listeners return true.)</p>
<p>iOS: Not applicable.</p>
<p>The event subscriptions are called in reverse order (i.e. last registered subscription first), and if one subscription returns true then subscriptions registered earlier will not be called.</p>
<p>Example:</p>
<pre><code class="hljs css language-javascript">BackHandler<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'hardwareBackPress'</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token comment">// this.onMainScreen and this.goBack are just examples, you need to use your own implementation here</span>
<span class="token comment">// Typically you would use the navigator here to go to the last state.</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">onMainScreen</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">goBack</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>Lifecycle example:</p>
<pre><code class="hljs css language-javascript"> <span class="token function">componentDidMount</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
BackHandler<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'hardwareBackPress'</span><span class="token punctuation">,</span> <span class="token keyword">this</span><span class="token punctuation">.</span>handleBackPress<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token function">componentWillUnmount</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
BackHandler<span class="token punctuation">.</span><span class="token function">removeEventListener</span><span class="token punctuation">(</span><span class="token string">'hardwareBackPress'</span><span class="token punctuation">,</span> <span class="token keyword">this</span><span class="token punctuation">.</span>handleBackPress<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token function-variable function">handleBackPress</span> <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">goBack</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// works best when the goBack is async</span>
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre>
<p>Lifecycle alternative:</p>
<pre><code class="hljs css language-javascript"> <span class="token function">componentDidMount</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">this</span><span class="token punctuation">.</span>backHandler <span class="token operator">=</span> BackHandler<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'hardwareBackPress'</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">{</span>
<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">goBack</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// works best when the goBack is async</span>
<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token function">componentWillUnmount</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">this</span><span class="token punctuation">.</span>backHandler<span class="token punctuation">.</span><span class="token function">remove</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="methods"></a><a href="#methods" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Methods</h3>
<ul>
<li><a href="/react-native/docs/backhandler#exitapp"><code>exitApp</code></a></li>
<li><a href="/react-native/docs/backhandler#addeventlistener"><code>addEventListener</code></a></li>
<li><a href="/react-native/docs/backhandler#removeeventlistener"><code>removeEventListener</code></a></li>
</ul>
<hr>
<h1><a class="anchor" aria-hidden="true" id="reference"></a><a href="#reference" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Reference</h1>
<h2><a class="anchor" aria-hidden="true" id="methods-1"></a><a href="#methods-1" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Methods</h2>
<h3><a class="anchor" aria-hidden="true" id="exitapp"></a><a href="#exitapp" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a><code>exitApp()</code></h3>
<pre><code class="hljs css language-javascript"><span class="token keyword">static</span> <span class="token function">exitApp</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
</code></pre>
<hr>
<h3><a class="anchor" aria-hidden="true" id="addeventlistener"></a><a href="#addeventlistener" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a><code>addEventListener()</code></h3>
<pre><code class="hljs css language-javascript"><span class="token keyword">static</span> <span class="token function">addEventListener</span><span class="token punctuation">(</span>eventName<span class="token punctuation">,</span> handler<span class="token punctuation">)</span>
</code></pre>
<hr>
<h3><a class="anchor" aria-hidden="true" id="removeeventlistener"></a><a href="#removeeventlistener" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a><code>removeEventListener()</code></h3>
<pre><code class="hljs css language-javascript"><span class="token keyword">static</span> <span class="token function">removeEventListener</span><span class="token punctuation">(</span>eventName<span class="token punctuation">,</span> handler<span class="token punctuation">)</span>
</code></pre>
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