React Native之函數(shù)作為參數(shù)傳遞給另外一個函數(shù)去調(diào)用

1 用法

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

 
2 代碼測試

寫了一個函數(shù),2個參數(shù)分別是函數(shù),然后更具數(shù)據(jù)決定調(diào)用哪個函數(shù)

    /**
     * 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 結(jié)果打印如下

很明顯,我們會調(diào)第二個參數(shù)的函數(shù),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 ON
                             I  chenzixuan
                             I  chenzixuan

 









作者：chen.yu
深信服三年半工作經(jīng)驗，目前就職游戲廠商，希望能和大家交流和學(xué)習(xí),
微信公眾號：編程入門到禿頭 或掃描下面二維碼
零基礎(chǔ)入門進階人工智能(鏈接)