React Native 的绑定 this

在React Native开发中,如果使用ES6语法的话,最好绑定this.但是使用ES5语法的话不需要绑定this.因为ES5会autobinding.

this所指的就是直至包含this指针的上层对象.

绑定this方法1:

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View
} from 'react-native';

export default class myProject extends Component {
  // 构造
    constructor(props) {
      super(props);
      // 初始状态
      this.state = {
        name:'shaoting',
          job:'coding'
      };
      //如果使用ES6编码 且 自定义方法里面需要使用到this .这时需要绑定this,否则报错
      //绑定this
        this.onclickOne = this.onclickOne.bind(this);
    }
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome} onPress={this.onclickOne}>
          Welcome to React Native!
        </Text>
        <Text style={styles.instructions}>
          To get started, edit index.ios.js
        </Text>
        <Text style={styles.instructions}>
          Press Cmd+R to reload,{'\n'}
          Cmd+D or shake for dev menu
        </Text>
      </View>
    );
  }
    onclickOne(){
       alert(this.state.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,
  },
});

AppRegistry.registerComponent('myProject', () => myProject);

绑定this方法2:

 /**
  * Sample React Native App
  * https://github.com/facebook/react-native
  * @flow
  */

 import React, { Component } from 'react';
 import {
   AppRegistry,
   StyleSheet,
   Text,
   View
 } from 'react-native';

 export default class myProject extends Component {
   // 构造
     constructor(props) {
       super(props);
       // 初始状态
       this.state = {
         name:'shaoting',
           job:'coding'
       };
     }
   render() {
     return (
       <View style={styles.container}>
         <Text style={styles.welcome} onPress={this.onclickOne.bind(this)}>
           Welcome to React Native!
         </Text>
         <Text style={styles.instructions}>
           To get started, edit index.ios.js
         </Text>
         <Text style={styles.instructions}>
           Press Cmd+R to reload,{'\n'}
           Cmd+D or shake for dev menu
         </Text>
       </View>
     );
   }
41     onclickOne(){
42        alert(this.state.name);
43     }
 }

 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,
   },
 });

 AppRegistry.registerComponent('myProject', () => myProject);

绑定this方法3(推荐):

 /**
  * Sample React Native App
  * https://github.com/facebook/react-native
  * @flow
  */

 import React, { Component } from 'react';
 import {
   AppRegistry,
   StyleSheet,
   Text,
   View
 } from 'react-native';

 export default class myProject extends Component {
   // 构造
     constructor(props) {
       super(props);
       // 初始状态
       this.state = {
         name:'shaoting',
           job:'coding'
       };
     }
   render() {
     return (
       <View style={styles.container}>
         <Text style={styles.welcome} onPress={this.onclickOne}>
           Welcome to React Native!
         </Text>
         <Text style={styles.instructions}>
           To get started, edit index.ios.js
         </Text>
         <Text style={styles.instructions}>
           Press Cmd+R to reload,{'\n'}
           Cmd+D or shake for dev menu
         </Text>
       </View>
     );
   }
41     onclickOne = () =>{
42        alert(this.state.name);
43     }
 }

 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,
   },
 });

 AppRegistry.registerComponent('myProject', () => myProject);