1 用法

我們一般喜歡把js里面的函數作為參數傳遞給另外一個函數,然后再調用這個函數,有點像C語言里面的函數指針

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2 代碼測試

寫了一個函數,2個參數分別是函數,然后更具數據決定調用哪個函數

/*** Sample React Native App* https://github.com/facebook/react-native** @format* @flow*/import React, {Component} from 'react'; import {Platform, StyleSheet, Text, View, NativeModules} from 'react-native';const instructions = Platform.select({ios: 'Press Cmd+R to reload,\n' + 'Cmd+D or shake for dev menu',android:'Double tap R on your keyboard to reload,\n' +'Shake or press menu button for dev menu', }); export default class App extends Component<Props> {constructor(props){super(props);this.state={myName:'chenzixuan',}}componentDidMount() { this.load((name) => {console.log(name);}, (name) => {console.log(name); console.log(name);});}render() {return (<View style={styles.container}><Text onPress={()=> this._androidShowMsg()} style={styles.welcome}>Welcome to React Native!</Text><Text style={styles.instructions}>To get started, edit App.js</Text><Text style={styles.instructions}>{instructions}</Text><Text style={styles.instructions}>{this.state.myName}</Text></View>);}load = (resolve, callback) => {let name = this.state.myName;if (name === 'chenzi1xuan') {resolve(name); } else {callback(name); }}; }const styles = StyleSheet.create({container: {flex: 1,justifyContent: 'center',alignItems: 'center',backgroundColor: '#F5FCFF',},welcome: {fontSize: 20,textAlign: 'center',margin: 10,},instructions: {textAlign: 'center',color: '#333333',marginBottom: 5,}, });

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3 結果打印如下

很明顯,我們會調第二個參數的函數,所以日志會打印兩次name,日志如下

ReactNativeJS I Running application "pro_react" with appParams: {"rootTag":1}. __DEV__ === false, development-level warning are OFF, performance optimizations are ONI chenzixuanI chenzixuan

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總結

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