本文共 1876 字，大约阅读时间需要 6 分钟。

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
   
     {       constructor(props){        super(props);        this.state={            myName:'chenzixuan',        }    }   componentDidMount() { 	this.load((name) => {console.log(name);}, (name) => {console.log(name); console.log(name);});   }  render() {    return (      
            
     
       this._androidShowMsg()} style={styles.welcome}>Welcome to React Native!
             
     
      To get started, edit App.js
             
     
      {instructions}
             
     
      {this.state.myName}
           
        );  }  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 ON                         I  chenzixuan                         I  chenzixuan

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