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<!DOCTYPE html><html><head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"><title>Timers – React Native | A framework for building native apps using React</title><meta name="viewport" content="width=device-width"><meta property="og:title" content="Timers – React Native | A framework for building native apps using React"><meta property="og:type" content="website"><meta property="og:url" content="http://facebook.github.io/react-native/index.html"><meta property="og:image" content="http://facebook.github.io/react-native/img/opengraph.png?2"><meta property="og:description" content="A framework for building native apps using React"><base href="/react-native/"><link rel="stylesheet" href="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css"><link rel="shortcut icon" href="img/favicon.png?2"><link rel="stylesheet" href="css/react-native.css"><script type="text/javascript" src="//use.typekit.net/vqa1hcx.js"></script><script type="text/javascript">try{Typekit.load();}catch(e){}</script></head><body><div class="container"><div class="nav-main"><div class="wrap"><a class="nav-home" href=""><img src="img/header_logo.png">React Native</a><a class="nav-version" href="/react-native/versions.html">0.33</a><div class="nav-site-wrapper"><ul class="nav-site nav-site-internal"><li><a href="docs/getting-started.html" class="active" data-target=".nav-docs">Docs</a></li><li><a href="support.html" class="">Support</a></li><li><a href="showcase.html" class="">Showcase</a></li><li><a href="blog/" class="">Blog</a></li></ul><div class="algolia-search-wrapper"><input id="algolia-doc-search" tabindex="0" type="text" placeholder="Search docs..."></div><ul class="nav-site nav-site-external"><li><a href="https://github.com/facebook/react-native" class="">GitHub</a></li><li><a href="http://facebook.github.io/react" class="">React</a></li></ul></div></div></div><section class="content wrap documentationContent"><div class="nav-docs"><div class="nav-docs-viewport"><div class="nav-docs-section"><h3>The Basics</h3><ul><li><a style="margin-left:0;" class="" href="docs/getting-started.html">Getting Started</a></li><li><a style="margin-left:0;" class="" href="docs/tutorial.html">Tutorial</a></li><li><a style="margin-left:0;" class="" href="docs/props.html">Props</a></li><li><a style="margin-left:0;" class="" href="docs/state.html">State</a></li><li><a style="margin-left:0;" class="" href="docs/style.html">Style</a></li><li><a style="margin-left:0;" class="" href="docs/height-and-width.html">Height and Width</a></li><li><a style="margin-left:0;" class="" href="docs/flexbox.html">Layout with Flexbox</a></li><li><a style="margin-left:0;" class="" href="docs/handling-text-input.html">Handling Text Input</a></li><li><a style="margin-left:0;" class="" href="docs/using-a-scrollview.html">Using a ScrollView</a></li><li><a style="margin-left:0;" class="" href="docs/using-a-listview.html">Using a ListView</a></li><li><a style="margin-left:0;" class="" href="docs/network.html">Networking</a></li><li><a style="margin-left:0;" class="" href="docs/using-navigators.html">Using Navigators</a></li><li><a style="margin-left:0;" class="" href="docs/more-resources.html">More Resources</a></li></ul></div><div class="nav-docs-section"><h3>Guides</h3><ul><li><a style="margin-left:0;" class="" href="docs/integration-with-existing-apps.html">Integration With Existing Apps</a></li><li><a style="margin-left:0;" class="" href="docs/colors.html">Colors</a></li><li><a style="margin-left:0;" class="" href="docs/images.html">Images</a></li><li><a style="margin-left:0;" class="" href="docs/handling-touches.html">Handling Touches</a></li><li><a style="margin-left:0;" class="" href="docs/animations.html">Animations</a></li><li><a style="margin-left:0;" class="" href="docs/accessibility.html">Accessibility</a></li><li><a style="margin-left:0;" class="active" href="docs/timers.html">Timers</a></li><li><a style="margin-left:0;" class="" href="docs/direct-manipulation.html">Direct Manipulation</a></li><li><a style="margin-left:0;" class="" href="docs/debugging.html">Debugging</a></li><li><a style="margin-left:0;" class="" href="docs/testing.html">Testing</a></li><li><a style="margin-left:0;" class="" href="docs/javascript-environment.html">JavaScript Environment</a></li><li><a style="margin-left:0;" class="" href="docs/navigation.html">Navigation</a></li><li><a style="margin-left:0;" class="" href="docs/performance.html">Performance</a></li><li><a style="margin-left:0;" class="" href="docs/upgrading.html">Upgrading</a></li><li><a style="margin-left:0;" class="" href="docs/platform-specific-code.html">Platform Specific Code</a></li><li><a style="margin-left:0;" class="" href="docs/gesture-responder-system.html">Gesture Responder System</a></li></ul></div><div class="nav-docs-section"><h3>Guides (iOS)</h3><ul><li><a style="margin-left:0;" class="" href="docs/native-modules-ios.html">Native Modules</a></li><li><a style="margin-left:0;" class="" href="docs/native-components-ios.html">Native UI Components</a></li><li><a style="margin-left:0;" class="" href="docs/linking-libraries-ios.html">Linking Libraries</a></li><li><a style="margin-left:0;" class="" href="docs/running-on-device-ios.html">Running On Device</a></li><li><a style="margin-left:0;" class="" href="docs/running-on-simulator-ios.html">Running On Simulator</a></li><li><a style="margin-left:0;" class="" href="docs/communication-ios.html">Communication between native and React Native</a></li></ul></div><div class="nav-docs-section"><h3>Guides (Android)</h3><ul><li><a style="margin-left:0;" class="" href="docs/native-modules-android.html">Native Modules</a></li><li><a style="margin-left:0;" class="" href="docs/native-components-android.html">Native UI Components</a></li><li><a style="margin-left:0;" class="" href="docs/running-on-device-android.html">Running On Device</a></li><li><a style="margin-left:0;" class="" href="docs/signed-apk-android.html">Generating Signed APK</a></li><li><a style="margin-left:0;" class="" href="docs/android-ui-performance.html">Profiling Android UI Performance</a></li><li><a style="margin-left:0;" class="" href="docs/android-building-from-source.html">Building React Native from source</a></li></ul></div><div class="nav-docs-section"><h3>components</h3><ul><li><a style="margin-left:0;" class="" href="docs/activityindicator.html">ActivityIndicator</a></li><li><a style="margin-left:0;" class="" href="docs/activityindicatorios.html">ActivityIndicatorIOS</a></li><li><a style="margin-left:0;" class="" href="docs/datepickerios.html">DatePickerIOS</a></li><li><a style="margin-left:0;" class="" href="docs/drawerlayoutandroid.html">DrawerLayoutAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/image.html">Image</a></li><li><a style="margin-left:0;" class="" href="docs/listview.html">ListView</a></li><li><a style="margin-left:0;" class="" href="docs/mapview.html">MapView</a></li><li><a style="margin-left:0;" class="" href="docs/modal.html">Modal</a></li><li><a style="margin-left:0;" class="" href="docs/navigator.html">Navigator</a></li><li><a style="margin-left:0;" class="" href="docs/navigatorios.html">NavigatorIOS</a></li><li><a style="margin-left:0;" class="" href="docs/picker.html">Picker</a></li><li><a style="margin-left:0;" class="" href="docs/pickerios.html">PickerIOS</a></li><li><a style="margin-left:0;" class="" href="docs/progressbarandroid.html">ProgressBarAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/progressviewios.html">ProgressViewIOS</a></li><li><a style="margin-left:0;" class="" href="docs/refreshcontrol.html">RefreshControl</a></li><li><a style="margin-left:0;" class="" href="docs/scrollview.html">ScrollView</a></li><li><a style="margin-left:0;" class="" href="docs/segmentedcontrolios.html">SegmentedControlIOS</a></li><li><a style="margin-left:0;" class="" href="docs/slider.html">Slider</a></li><li><a style="margin-left:0;" class="" href="docs/sliderios.html">SliderIOS</a></li><li><a style="margin-left:0;" class="" href="docs/statusbar.html">StatusBar</a></li><li><a style="margin-left:0;" class="" href="docs/snapshotviewios.html">SnapshotViewIOS</a></li><li><a style="margin-left:0;" class="" href="docs/switch.html">Switch</a></li><li><a style="margin-left:0;" class="" href="docs/switchandroid.html">SwitchAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/switchios.html">SwitchIOS</a></li><li><a style="margin-left:0;" class="" href="docs/tabbarios.html">TabBarIOS</a></li><li><a style="margin-left:0;" class="" href="docs/tabbarios-item.html">TabBarIOS.Item</a></li><li><a style="margin-left:0;" class="" href="docs/text.html">Text</a></li><li><a style="margin-left:0;" class="" href="docs/textinput.html">TextInput</a></li><li><a style="margin-left:0;" class="" href="docs/toolbarandroid.html">ToolbarAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/touchablehighlight.html">TouchableHighlight</a></li><li><a style="margin-left:0;" class="" href="docs/touchablenativefeedback.html">TouchableNativeFeedback</a></li><li><a style="margin-left:0;" class="" href="docs/touchableopacity.html">TouchableOpacity</a></li><li><a style="margin-left:0;" class="" href="docs/touchablewithoutfeedback.html">TouchableWithoutFeedback</a></li><li><a style="margin-left:0;" class="" href="docs/view.html">View</a></li><li><a style="margin-left:0;" class="" href="docs/viewpagerandroid.html">ViewPagerAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/webview.html">WebView</a></li></ul></div><div class="nav-docs-section"><h3>apis</h3><ul><li><a style="margin-left:0;" class="" href="docs/actionsheetios.html">ActionSheetIOS</a></li><li><a style="margin-left:0;" class="" href="docs/adsupportios.html">AdSupportIOS</a></li><li><a style="margin-left:0;" class="" href="docs/alert.html">Alert</a></li><li><a style="margin-left:0;" class="" href="docs/alertios.html">AlertIOS</a></li><li><a style="margin-left:0;" class="" href="docs/animated.html">Animated</a></li><li><a style="margin-left:0;" class="" href="docs/appregistry.html">AppRegistry</a></li><li><a style="margin-left:0;" class="" href="docs/appstate.html">AppState</a></li><li><a style="margin-left:0;" class="" href="docs/asyncstorage.html">AsyncStorage</a></li><li><a style="margin-left:0;" class="" href="docs/backandroid.html">BackAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/cameraroll.html">CameraRoll</a></li><li><a style="margin-left:0;" class="" href="docs/clipboard.html">Clipboard</a></li><li><a style="margin-left:0;" class="" href="docs/datepickerandroid.html">DatePickerAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/dimensions.html">Dimensions</a></li><li><a style="margin-left:0;" class="" href="docs/easing.html">Easing</a></li><li><a style="margin-left:0;" class="" href="docs/geolocation.html">Geolocation</a></li><li><a style="margin-left:0;" class="" href="docs/imageeditor.html">ImageEditor</a></li><li><a style="margin-left:0;" class="" href="docs/imagepickerios.html">ImagePickerIOS</a></li><li><a style="margin-left:0;" class="" href="docs/imagestore.html">ImageStore</a></li><li><a style="margin-left:0;" class="" href="docs/intentandroid.html">IntentAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/interactionmanager.html">InteractionManager</a></li><li><a style="margin-left:0;" class="" href="docs/layoutanimation.html">LayoutAnimation</a></li><li><a style="margin-left:0;" class="" href="docs/linking.html">Linking</a></li><li><a style="margin-left:0;" class="" href="docs/nativemethodsmixin.html">NativeMethodsMixin</a></li><li><a style="margin-left:0;" class="" href="docs/nativemodules.html">NativeModules</a></li><li><a style="margin-left:0;" class="" href="docs/netinfo.html">NetInfo</a></li><li><a style="margin-left:0;" class="" href="docs/panresponder.html">PanResponder</a></li><li><a style="margin-left:0;" class="" href="docs/permissionsandroid.html">PermissionsAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/pixelratio.html">PixelRatio</a></li><li><a style="margin-left:0;" class="" href="docs/pushnotificationios.html">PushNotificationIOS</a></li><li><a style="margin-left:0;" class="" href="docs/settings.html">Settings</a></li><li><a style="margin-left:0;" class="" href="docs/statusbarios.html">StatusBarIOS</a></li><li><a style="margin-left:0;" class="" href="docs/stylesheet.html">StyleSheet</a></li><li><a style="margin-left:0;" class="" href="docs/systrace.html">Systrace</a></li><li><a style="margin-left:0;" class="" href="docs/timepickerandroid.html">TimePickerAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/toastandroid.html">ToastAndroid</a></li><li><a style="margin-left:0;" class="" href="docs/vibration.html">Vibration</a></li><li><a style="margin-left:0;" class="" href="docs/vibrationios.html">VibrationIOS</a></li><li><a style="margin-left:0;" class="" href="docs/layout-props.html">Layout Props</a></li><li><a style="margin-left:0;" class="" href="docs/shadow-props.html">Shadow Props</a></li></ul></div></div></div><div class="inner-content"><a id="content"></a><h1><a class="anchor" name="timers"></a>Timers <a class="hash-link" href="docs/timers.html#timers">#</a></h1><div><p>Timers are an important part of an application and React Native implements the <a href="https://developer.mozilla.org/en-US/Add-ons/Code_snippets/Timers" target="_blank">browser timers</a>.</p><h2><a class="anchor" name="timers"></a>Timers <a class="hash-link" href="docs/timers.html#timers">#</a></h2><ul><li>setTimeout, clearTimeout</li><li>setInterval, clearInterval</li><li>setImmediate, clearImmediate</li><li>requestAnimationFrame, cancelAnimationFrame</li></ul><p><code>requestAnimationFrame(fn)</code> is not the same as <code>setTimeout(fn, 0)</code> - the former will fire after all the frame has flushed, whereas the latter will fire as quickly as possible (over 1000x per second on a iPhone 5S).</p><p><code>setImmediate</code> is executed at the end of the current JavaScript execution block, right before sending the batched response back to native. Note that if you call <code>setImmediate</code> within a <code>setImmediate</code> callback, it will be executed right away, it won't yield back to native in between.</p><p>The <code>Promise</code> implementation uses <code>setImmediate</code> as its asynchronicity primitive.</p><h2><a class="anchor" name="interactionmanager"></a>InteractionManager <a class="hash-link" href="docs/timers.html#interactionmanager">#</a></h2><p>One reason why well-built native apps feel so smooth is by avoiding expensive operations during interactions and animations. In React Native, we currently have a limitation that there is only a single JS execution thread, but you can use <code>InteractionManager</code> to make sure long-running work is scheduled to start after any interactions/animations have completed.</p><p>Applications can schedule tasks to run after interactions with the following:</p><div class="prism language-javascript">InteractionManager<span class="token punctuation">.</span><span class="token function">runAfterInteractions<span class="token punctuation">(</span></span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
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<span class="token comment" spellcheck="true"> // ...long-running synchronous task...
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</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span></div><p>Compare this to other scheduling alternatives:</p><ul><li>requestAnimationFrame(): for code that animates a view over time.</li><li>setImmediate/setTimeout/setInterval(): run code later, note this may delay animations.</li><li>runAfterInteractions(): run code later, without delaying active animations.</li></ul><p>The touch handling system considers one or more active touches to be an 'interaction' and will delay <code>runAfterInteractions()</code> callbacks until all touches have ended or been cancelled.</p><p>InteractionManager also allows applications to register animations by creating an interaction 'handle' on animation start, and clearing it upon completion:</p><div class="prism language-javascript"><span class="token keyword">var</span> handle <span class="token operator">=</span> InteractionManager<span class="token punctuation">.</span><span class="token function">createInteractionHandle<span class="token punctuation">(</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment" spellcheck="true">
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// run animation... (`runAfterInteractions` tasks are queued)
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</span><span class="token comment" spellcheck="true">// later, on animation completion:
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</span>InteractionManager<span class="token punctuation">.</span><span class="token function">clearInteractionHandle<span class="token punctuation">(</span></span>handle<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment" spellcheck="true">
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// queued tasks run if all handles were cleared</span></div><h2><a class="anchor" name="timermixin"></a>TimerMixin <a class="hash-link" href="docs/timers.html#timermixin">#</a></h2><p>We found out that the primary cause of fatals in apps created with React Native was due to timers firing after a component was unmounted. To solve this recurring issue, we introduced <code>TimerMixin</code>. If you include <code>TimerMixin</code>, then you can replace your calls to <code>setTimeout(fn, 500)</code> with <code>this.setTimeout(fn, 500)</code> (just prepend <code>this.</code>) and everything will be properly cleaned up for you when the component unmounts.</p><p>This library does not ship with React Native - in order to use it on your project, you will need to install it with <code>npm i react-timer-mixin --save</code> from your project directory.</p><div class="prism language-javascript">import TimerMixin from <span class="token string">'react-timer-mixin'</span><span class="token punctuation">;</span>
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<span class="token keyword">var</span> Component <span class="token operator">=</span> React<span class="token punctuation">.</span><span class="token function">createClass<span class="token punctuation">(</span></span><span class="token punctuation">{</span>
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mixins<span class="token punctuation">:</span> <span class="token punctuation">[</span>TimerMixin<span class="token punctuation">]</span><span class="token punctuation">,</span>
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componentDidMount<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>
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<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setTimeout<span class="token punctuation">(</span></span>
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<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span> console<span class="token punctuation">.</span><span class="token function">log<span class="token punctuation">(</span></span><span class="token string">'I do not leak!'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">,</span>
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<span class="token number">500</span>
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<span class="token punctuation">)</span><span class="token punctuation">;</span>
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<span class="token punctuation">}</span>
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<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span></div><p>This will eliminate a lot of hard work tracking down bugs, such as crashes caused by timeouts firing after a component has been unmounted.</p><p>Keep in mind that if you use ES6 classes for your React components <a href="https://facebook.github.io/react/blog/2015/01/27/react-v0.13.0-beta-1.html#mixins" target="_blank">there is no built-in API for mixins</a>. To use <code>TimerMixin</code> with ES6 classes, we recommend <a href="https://github.com/brigand/react-mixin" target="_blank">react-mixin</a>.</p></div><div class="docs-prevnext"><a class="docs-prev" href="docs/accessibility.html#content">← Prev</a><a class="docs-next" href="docs/direct-manipulation.html#content">Next →</a></div><p class="edit-page-block">You can <a target="_blank" href="https://github.com/facebook/react-native/blob/master/docs/Timers.md">edit the content above on GitHub</a> and send us a pull request!</p><div class="survey"><div class="survey-image"></div><p>Recently, we have been working hard to make the documentation better based on your feedback. Your responses to this yes/no style survey will help us gauge whether we moved in the right direction with the improvements. Thank you!</p><center><a class="button" href="https://www.facebook.com/survey?oid=516954245168428">Take Survey</a></center></div></div></section><footer class="wrap"><div class="center">© 2016 Facebook Inc.</div></footer></div><div id="fb-root"></div><script type="text/javascript" src="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.js"></script><script>
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