1 用法

我们一般喜欢把js里面的函数作为参数传递给另外一个函数,然后再调用这个函数,有点像C语言里面的函数指针

 

 

 

 

2 代码测试

写了一个函数,2个参数分别是函数,然后更具数据决定调用哪个函数

/*** 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,},
});

 

 

3 结果打印如下

很明显,我们会调第二个参数的函数,所以日志会打印两次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