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<!DOCTYPE html><html><head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"><title>Direct Manipulation – React Native | A framework for building native apps using React</title><meta name="viewport" content="width=device-width"><meta property="og:title" content="Direct Manipulation – 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"><link rel="stylesheet" href="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css"><link rel="shortcut icon" href="/react-native/img/favicon.png?2"><link rel="stylesheet" href="/react-native/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="/react-native/"><img src="/react-native/img/header_logo.png">React Native</a><div class="nav-site-wrapper"><ul class="nav-site nav-site-internal"><li><a href="/react-native/docs/getting-started.html" class="active">Docs</a></li><li><a href="/react-native/support.html" class="">Support</a></li><li><a href="https://github.com/facebook/react-native/releases" class="">Releases</a></li><li><a href="http://reactnative.cc" class="">Newsletter</a></li><li><a href="/react-native/showcase.html" class="">Showcase</a></li></ul><div class="algolia-search-wrapper"><input id="algolia-doc-search" 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-section"><h3>Quick Start</h3><ul><li><a style="margin-left:0;" class="" href="/react-native/docs/getting-started.html#content">Getting Started</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/android-setup.html#content">Android Setup</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/linux-windows-support.html#content">Linux and Windows Support</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/tutorial.html#content">Tutorial</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/videos.html#content">Videos</a></li></ul></div><div class="nav-docs-section"><h3>Guides</h3><ul><li><a style="margin-left:0;" class="" href="/react-native/docs/style.html#content">Style</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/images.html#content">Images</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/gesture-responder-system.html#content">Gesture Responder System</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/animations.html#content">Animations</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/accessibility.html#content">Accessibility</a></li><li><a style="margin-left:0;" class="active" href="/react-native/docs/direct-manipulation.html#content">Direct Manipulation</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/debugging.html#content">Debugging</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/testing.html#content">Testing</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/javascript-environment.html#content">JavaScript Environment</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/navigator-comparison.html#content">Navigator Comparison</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/known-issues.html#content">Known Issues</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/performance.html#content">Performance</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/upgrading.html#content">Upgrading</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/platform-specific-code.html#content">Platform Specific Code</a></li></ul></div><div class="nav-docs-section"><h3>Guides (iOS)</h3><ul><li><a style="margin-left:0;" class="" href="/react-native/docs/native-modules-ios.html#content">Native Modules</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/native-components-ios.html#content">Native UI Components</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/linking-libraries-ios.html#content">Linking Libraries</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/running-on-device-ios.html#content">Running On Device</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/embedded-app-ios.html#content">Integrating with Existing Apps</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/communication-ios.html#content">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="/react-native/docs/native-modules-android.html#content">Native Modules</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/native-components-android.html#content">Native UI Components</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/running-on-device-android.html#content">Running On Device</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/embedded-app-android.html#content">Integrating with Existing Apps</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/signed-apk-android.html#content">Generating Signed APK</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/android-ui-performance.html#content">Profiling Android UI Performance</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/android-building-from-source.html#content">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="/react-native/docs/activityindicatorios.html#content">ActivityIndicatorIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/datepickerios.html#content">DatePickerIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/drawerlayoutandroid.html#content">DrawerLayoutAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/image.html#content">Image</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/listview.html#content">ListView</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/mapview.html#content">MapView</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/modal.html#content">Modal</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/navigator.html#content">Navigator</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/navigatorios.html#content">NavigatorIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/pickerios.html#content">PickerIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/progressbarandroid.html#content">ProgressBarAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/progressviewios.html#content">ProgressViewIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/pulltorefreshviewandroid.html#content">PullToRefreshViewAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/refreshcontrol.html#content">RefreshControl</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/scrollview.html#content">ScrollView</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/segmentedcontrolios.html#content">SegmentedControlIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/sliderios.html#content">SliderIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/switch.html#content">Switch</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/tabbarios.html#content">TabBarIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/tabbarios-item.html#content">TabBarIOS.Item</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/text.html#content">Text</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/textinput.html#content">TextInput</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/toolbarandroid.html#content">ToolbarAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/touchablehighlight.html#content">TouchableHighlight</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/touchablenativefeedback.html#content">TouchableNativeFeedback</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/touchableopacity.html#content">TouchableOpacity</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/touchablewithoutfeedback.html#content">TouchableWithoutFeedback</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/view.html#content">View</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/viewpagerandroid.html#content">ViewPagerAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/webview.html#content">WebView</a></li></ul></div><div class="nav-docs-section"><h3>apis</h3><ul><li><a style="margin-left:0;" class="" href="/react-native/docs/actionsheetios.html#content">ActionSheetIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/alert.html#content">Alert</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/alertios.html#content">AlertIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/animated.html#content">Animated</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/appregistry.html#content">AppRegistry</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/appstateios.html#content">AppStateIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/asyncstorage.html#content">AsyncStorage</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/backandroid.html#content">BackAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/cameraroll.html#content">CameraRoll</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/dimensions.html#content">Dimensions</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/intentandroid.html#content">IntentAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/interactionmanager.html#content">InteractionManager</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/layoutanimation.html#content">LayoutAnimation</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/linkingios.html#content">LinkingIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/nativemethodsmixin.html#content">NativeMethodsMixin</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/netinfo.html#content">NetInfo</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/panresponder.html#content">PanResponder</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/pixelratio.html#content">PixelRatio</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/pushnotificationios.html#content">PushNotificationIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/statusbarios.html#content">StatusBarIOS</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/stylesheet.html#content">StyleSheet</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/toastandroid.html#content">ToastAndroid</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/vibrationios.html#content">VibrationIOS</a></li></ul></div><div class="nav-docs-section"><h3>Polyfills</h3><ul><li><a style="margin-left:0;" class="" href="/react-native/docs/flexbox.html#content">Flexbox</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/geolocation.html#content">Geolocation</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/network.html#content">Network</a></li><li><a style="margin-left:0;" class="" href="/react-native/docs/timers.html#content">Timers</a></li></ul></div></div><div class="inner-content"><a id="content"></a><h1>Direct Manipulation</h1><div><p>It is sometimes necessary to make changes directly to a component
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without using state/props to trigger a re-render of the entire subtree.
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When using React in the browser for example, you sometimes need to
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directly modify a DOM node, and the same is true for views in mobile
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apps. <code>setNativeProps</code> is the React Native equivalent to setting
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properties directly on a DOM node.</p><blockquote><p>Use setNativeProps when frequent re-rendering creates a performance bottleneck</p><p>Direct manipulation will not be a tool that you reach for
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frequently; you will typically only be using it for creating
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continuous animations to avoid the overhead of rendering the component
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hierarchy and reconciling many views. <code>setNativeProps</code> is imperative
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and stores state in the native layer (DOM, UIView, etc.) and not
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within your React components, which makes your code more difficult to
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reason about. Before you use it, try to solve your problem with <code>setState</code>
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and <a href="react-native/docs/direct-manipulation.html#setnativeprops-shouldcomponentupdate" target="_blank">shouldComponentUpdate</a>.</p></blockquote><h2><a class="anchor" name="setnativeprops-with-touchableopacity"></a>setNativeProps with TouchableOpacity <a class="hash-link" href="#setnativeprops-with-touchableopacity">#</a></h2><p><a href="https://github.com/facebook/react-native/blob/master/Libraries/Components/Touchable/TouchableOpacity.js" target="_blank">TouchableOpacity</a>
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uses <code>setNativeProps</code> internally to update the opacity of its child
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component:</p><div class="prism language-javascript">setOpacityTo<span class="token punctuation">:</span> <span class="token keyword">function</span><span class="token punctuation">(</span>value<span class="token punctuation">)</span> <span class="token punctuation">{</span>
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<span class="token comment" spellcheck="true"> // Redacted: animation related code
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</span> <span class="token keyword">this</span><span class="token punctuation">.</span>refs<span class="token punctuation">[</span>CHILD_REF<span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function">setNativeProps<span class="token punctuation">(</span></span><span class="token punctuation">{</span>
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opacity<span class="token punctuation">:</span> value
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<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
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<span class="token punctuation">}</span><span class="token punctuation">,</span></div><p>This allows us to write the following code and know that the child will
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have its opacity updated in response to taps, without the child having
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any knowledge of that fact or requiring any changes to its implementation:</p><div class="prism language-javascript"><TouchableOpacity onPress<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>_handlePress<span class="token punctuation">}</span><span class="token operator">></span>
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<View style<span class="token operator">=</span><span class="token punctuation">{</span>styles<span class="token punctuation">.</span>button<span class="token punctuation">}</span><span class="token operator">></span>
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<Text<span class="token operator">></span>Press me<span class="token operator">!</span><<span class="token operator">/</span>Text<span class="token operator">></span>
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<<span class="token operator">/</span>View<span class="token operator">></span>
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<TouchableOpacity<span class="token operator">></span></div><p>Let's imagine that <code>setNativeProps</code> was not available. One way that we
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might implement it with that constraint is to store the opacity value
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in the state, then update that value whenever <code>onPress</code> is fired:</p><div class="prism language-javascript"><span class="token function">getInitialState<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
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<span class="token keyword">return</span> <span class="token punctuation">{</span> myButtonOpacity<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token punctuation">}</span>
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<span class="token punctuation">}</span><span class="token punctuation">,</span>
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<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
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<span class="token keyword">return</span> <span class="token punctuation">(</span>
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<TouchableOpacity onPress<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState<span class="token punctuation">(</span></span><span class="token punctuation">{</span>myButtonOpacity<span class="token punctuation">:</span> <span class="token number">0.5</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">}</span>
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onPressOut<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState<span class="token punctuation">(</span></span><span class="token punctuation">{</span>myButtonOpacity<span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">}</span><span class="token operator">></span>
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<View style<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">[</span>styles<span class="token punctuation">.</span>button<span class="token punctuation">,</span> <span class="token punctuation">{</span>opacity<span class="token punctuation">:</span> <span class="token keyword">this</span><span class="token punctuation">.</span>state<span class="token punctuation">.</span>myButtonOpacity<span class="token punctuation">}</span><span class="token punctuation">]</span><span class="token punctuation">}</span><span class="token operator">></span>
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<Text<span class="token operator">></span>Press me<span class="token operator">!</span><<span class="token operator">/</span>Text<span class="token operator">></span>
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<<span class="token operator">/</span>View<span class="token operator">></span>
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<<span class="token operator">/</span>TouchableOpacity<span class="token operator">></span>
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<span class="token punctuation">)</span>
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<span class="token punctuation">}</span></div><p>This is computationally intensive compared to the original example -
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React needs to re-render the component hierarchy each time the opacity
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changes, even though other properties of the view and its children
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haven't changed. Usually this overhead isn't a concern but when
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performing continuous animations and responding to gestures, judiciously
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optimizing your components can improve your animations' fidelity.</p><p>If you look at the implementation of <code>setNativeProps</code> in
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<a href="https://github.com/facebook/react-native/blob/master/Libraries/ReactIOS/NativeMethodsMixin.js" target="_blank">NativeMethodsMixin.js</a>
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you will notice that it is a wrapper around <code>RCTUIManager.updateView</code> -
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this is the exact same function call that results from re-rendering -
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see <a href="https://github.com/facebook/react-native/blob/master/Libraries/ReactNative/ReactNativeBaseComponent.js" target="_blank">receiveComponent in
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ReactNativeBaseComponent.js</a>.</p><h2><a class="anchor" name="composite-components-and-setnativeprops"></a>Composite components and setNativeProps <a class="hash-link" href="#composite-components-and-setnativeprops">#</a></h2><p>Composite components are not backed by a native view, so you cannot call
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<code>setNativeProps</code> on them. Consider this example:</p><div class="prism language-javascript"><span class="token keyword">var</span> MyButton <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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<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
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<span class="token keyword">return</span> <span class="token punctuation">(</span>
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<View<span class="token operator">></span>
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<Text<span class="token operator">></span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>label<span class="token punctuation">}</span><<span class="token operator">/</span>Text<span class="token operator">></span>
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<<span class="token operator">/</span>View<span class="token operator">></span>
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<span class="token punctuation">)</span>
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<span class="token punctuation">}</span><span class="token punctuation">,</span>
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<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
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<span class="token keyword">var</span> App <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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<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
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<span class="token keyword">return</span> <span class="token punctuation">(</span>
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<TouchableOpacity<span class="token operator">></span>
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<MyButton label<span class="token operator">=</span><span class="token string">"Press me!"</span> <span class="token operator">/</span><span class="token operator">></span>
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<<span class="token operator">/</span>TouchableOpacity<span class="token operator">></span>
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<span class="token punctuation">)</span>
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<span class="token punctuation">}</span><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><a href="https://rnplay.org/apps/JXkgmQ" target="_blank">Run this example</a></p><p>If you run this you will immediately see this error: <code>Touchable child
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must either be native or forward setNativeProps to a native component</code>.
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This occurs because <code>MyButton</code> isn't directly backed by a native view
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whose opacity should be set. You can think about it like this: if you
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define a component with <code>React.createClass</code> you would not expect to be
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able to set a style prop on it and have that work - you would need to
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pass the style prop down to a child, unless you are wrapping a native
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component. Similarly, we are going to forward <code>setNativeProps</code> to a
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native-backed child component.</p><h4><a class="anchor" name="forward-setnativeprops-to-a-child"></a>Forward setNativeProps to a child <a class="hash-link" href="#forward-setnativeprops-to-a-child">#</a></h4><p>All we need to do is provide a <code>setNativeProps</code> method on our component
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that calls <code>setNativeProps</code> on the appropriate child with the given
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arguments.</p><div class="prism language-javascript"><span class="token keyword">var</span> MyButton <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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<span class="token function">setNativeProps<span class="token punctuation">(</span></span>nativeProps<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>_root<span class="token punctuation">.</span><span class="token function">setNativeProps<span class="token punctuation">(</span></span>nativeProps<span class="token punctuation">)</span><span class="token punctuation">;</span>
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<span class="token punctuation">}</span><span class="token punctuation">,</span>
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<span class="token function">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
||
<View ref<span class="token operator">=</span><span class="token punctuation">{</span>component <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span>_root <span class="token operator">=</span> component<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 keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">}</span><span class="token operator">></span>
|
||
<Text<span class="token operator">></span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>props<span class="token punctuation">.</span>label<span class="token punctuation">}</span><<span class="token operator">/</span>Text<span class="token operator">></span>
|
||
<<span class="token operator">/</span>View<span class="token operator">></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 punctuation">;</span></div><p><a href="https://rnplay.org/apps/YJxnEQ" target="_blank">Run this example</a></p><p>You can now use <code>MyButton</code> inside of <code>TouchableOpacity</code>! A sidenote for
|
||
clarity: we used the <a href="https://facebook.github.io/react/docs/more-about-refs.html#the-ref-callback-attribute" target="_blank">ref callback</a> syntax here, rather than the traditional string-based ref.</p><p>You may have noticed that we passed all of the props down to the child
|
||
view using <code>{...this.props}</code>. The reason for this is that
|
||
<code>TouchableOpacity</code> is actually a composite component, and so in addition
|
||
to depending on <code>setNativeProps</code> on its child, it also requires that the
|
||
child perform touch handling. To do this, it passes on <a href="https://facebook.github.io/react-native/docs/view.html#onmoveshouldsetresponder" target="_blank">various
|
||
props</a>
|
||
that call back to the <code>TouchableOpacity</code> component.
|
||
<code>TouchableHighlight</code>, in contrast, is backed by a native view and only
|
||
requires that we implement <code>setNativeProps</code>.</p><h2><a class="anchor" name="setnativeprops-to-clear-textinput-value"></a>setNativeProps to clear TextInput value <a class="hash-link" href="#setnativeprops-to-clear-textinput-value">#</a></h2><p>Another very common use case of <code>setNativeProps</code> is to clear the value
|
||
of a TextInput. The <code>controlled</code> prop of TextInput can sometimes drop
|
||
characters when the <code>bufferDelay</code> is low and the user types very
|
||
quickly. Some developers prefer to skip this prop entirely and instead
|
||
use <code>setNativeProps</code> to directly manipulate the TextInput value when
|
||
necessary. For example, the following code demonstrates clearing the
|
||
input when you tap a button:</p><div class="prism language-javascript"><span class="token keyword">var</span> App <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>
|
||
<span class="token function">clearText<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">this</span><span class="token punctuation">.</span>_textInput<span class="token punctuation">.</span><span class="token function">setNativeProps<span class="token punctuation">(</span></span><span class="token punctuation">{</span>text<span class="token punctuation">:</span> <span class="token string">''</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">render<span class="token punctuation">(</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||
<span class="token keyword">return</span> <span class="token punctuation">(</span>
|
||
<View style<span class="token operator">=</span><span class="token punctuation">{</span>styles<span class="token punctuation">.</span>container<span class="token punctuation">}</span><span class="token operator">></span>
|
||
<TextInput ref<span class="token operator">=</span><span class="token punctuation">{</span>component <span class="token operator">=</span><span class="token operator">></span> <span class="token keyword">this</span><span class="token punctuation">.</span>_textInput <span class="token operator">=</span> component<span class="token punctuation">}</span>
|
||
style<span class="token operator">=</span><span class="token punctuation">{</span>styles<span class="token punctuation">.</span>textInput<span class="token punctuation">}</span> <span class="token operator">/</span><span class="token operator">></span>
|
||
<TouchableOpacity onPress<span class="token operator">=</span><span class="token punctuation">{</span><span class="token keyword">this</span><span class="token punctuation">.</span>clearText<span class="token punctuation">}</span><span class="token operator">></span>
|
||
<Text<span class="token operator">></span>Clear text<<span class="token operator">/</span>Text<span class="token operator">></span>
|
||
<<span class="token operator">/</span>TouchableOpacity<span class="token operator">></span>
|
||
<<span class="token operator">/</span>View<span class="token operator">></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 punctuation">;</span></div><p><a href="https://rnplay.org/plays/pOI9bA" target="_blank">Run this example</a></p><h2><a class="anchor" name="avoiding-conflicts-with-the-render-function"></a>Avoiding conflicts with the render function <a class="hash-link" href="#avoiding-conflicts-with-the-render-function">#</a></h2><p>If you update a property that is also managed by the render function,
|
||
you might end up with some unpredictable and confusing bugs because
|
||
anytime the component re-renders and that property changes, whatever
|
||
value was previously set from <code>setNativeProps</code> will be completely
|
||
ignored and overridden. <a href="https://rnplay.org/apps/bp1DvQ" target="_blank">See this example</a>
|
||
for a demonstration of what can happen if these two collide - notice
|
||
the jerky animation each 250ms when <code>setState</code> triggers a re-render.</p><h2><a class="anchor" name="setnativeprops-shouldcomponentupdate"></a>setNativeProps & shouldComponentUpdate <a class="hash-link" href="#setnativeprops-shouldcomponentupdate">#</a></h2><p>By <a href="https://facebook.github.io/react/docs/advanced-performance.html#avoiding-reconciling-the-dom" target="_blank">intelligently applying
|
||
<code>shouldComponentUpdate</code></a>
|
||
you can avoid the unnecessary overhead involved in reconciling unchanged
|
||
component subtrees, to the point where it may be performant enough to
|
||
use <code>setState</code> instead of <code>setNativeProps</code>.</p></div><div class="docs-prevnext"><a class="docs-next" href="debugging.html#content">Next →</a></div></div></section><footer class="wrap"><div class="center">© 2015 Facebook Inc.</div></footer></div><div id="fb-root"></div><script>
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