标签:jsx ecmascript-6 reactjs syntax javascript
我正在关注本文(原始实现Sibling Sibling):
Update state cross component
该示例运行完美.但是,当我尝试将每个类分离到每个.js文件时,然后使用导入/导出互相调用/绑定.它(更新状态)不再起作用.
像这样的结构:
Sibling1.js
import React, { Component } from 'react';
<-- some declare style -->
export function updateText(text) {
this.setState({text})
}
export class Sibling1 extends Component {
render() {
return (
<div>
<div style={{ ...style.topLabel, color: secondaryColor }}>I am Sibling 1</div>
<input style={style.textBox} type="text"
placeholder="Write text" onChange={(e) => updateText(e.target.value)} />
</div>
)
}
}
Example.js
import React, { Component } from 'react';
import * as sibling1 from './Sibling1'; //is this good?
import {Sibling1} from './Sibling1'; //is this good?
<-- some declare style, variable -->
class Sibling2 extends Component {
constructor(props) {
super(props)
this.state = {
text: "Initial State"
}
sibling1.updateText = sibling1.updateText.bind(this) //is this good binding?
}
render() {
console.log('Sibling2.state : ', this.state);
return (
<div>
<div style={{ ...style.topLabel, color: primaryColor }}>I am Sibling 2</div>
<div style={style.label}>{this.state.text}</div>
</div>
)
}
}
class Example3 extends Component {
render() {
return (
<div>
<Sibling1 />
<Sibling2 />
</div>
)
}
}
export default Example3;
我只是希望Sibling1可以更改Sibling2的状态(就像原始实现一样),但是不能.
我猜我的bind(this)没有绑定正确的上下文.
有人可以告诉我原始实现(上面的文章)和我的方法(分离到多个.js文件)之间的区别是什么?
解决方法:
React kinda迫使您使用单向数据流.因此,您不能只是从Sibling2中更新Sibling1的状态.
正如Dinesh Pandiyan在他的示例中提到的那样,通常您将拥有一个控制两个兄弟姐妹状态的父组件.您的代码将如下所示:
Sibling1.js
import React, { Component } from 'react';
<-- some declare style -->
export class Sibling1 extends Component {
function updateText(text) {
// Use updateText function from props.
// Props are like state but not controlled by the component itself
// The value is passed to the component from outside
this.props.updateText(text)
}
render() {
return (
<div>
<div style={{ ...style.topLabel, color: secondaryColor }}>I am Sibling 1</div>
<input style={style.textBox} type="text"
placeholder="Write text"
onChange={(e) => this.updateText(e.target.value).bind(this)} />
</div>
)
}
}
Example.js
import React, { Component } from 'react';
import { Sibling1 } from './Sibling1'; // This is good.
import Sibling1 from './Sibling1'; // This is also possible if you use export default class instead of export class
<-- some declare style, variable -->
class Sibling2 extends Component {
// Use same function as in Sibling1.
function updateText(text) {
this.props.updateText(text)
}
render() {
return (
<div>
<div style={{ ...style.topLabel, color: primaryColor }}>I am Sibling 2</div>
<div style={style.label}>{this.props.text}</div> // changed state to props
</div>
)
}
}
class Example3 extends Component {
constructor(props) {
super(props);
this.state = {
text: "Initial state"
};
}
// Control state from parent component
function updateText(
this.setState({ text: text });
}
render() {
return (
<div>
<Sibling1 updateText={this.updateText.bind(this)}/>
<Sibling2 updateText={this.updateText.bind(this)} text={this.state.text} />
</div>
)
}
}
export default Example3;
标签:jsx,ecmascript-6,reactjs,syntax,javascript 来源: https://codeday.me/bug/20191108/2008191.html
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