React Native之函数作为参数传递给另外一个函数去调用

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 ON
                             I  chenzixuan
                             I  chenzixuan

 

作者：chen.yu
深信服三年半工作经验，目前就职游戏厂商，希望能和大家交流和学习,
微信公众号：编程入门到秃头 或扫描下面二维码
零基础入门进阶人工智能(链接)