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);