78 lines
2.6 KiB
HTML
78 lines
2.6 KiB
HTML
<!--
|
||
* @Author: chenxuan
|
||
* @Date: 2022-01-13 00:00:14
|
||
* @LastEditTime: 2022-04-05 23:14:03
|
||
* @LastEditors: chenxuan
|
||
-->
|
||
<!DOCTYPE html>
|
||
<html lang="en">
|
||
<head>
|
||
<meta charset="UTF-8">
|
||
<meta http-equiv="X-UA-Compatible" content="IE=edge">
|
||
<meta name="viewport" content="width=device-width, initial-scale=1.0">
|
||
<title>getDerivedStateFromProps</title>
|
||
<script src="../package/new/react.development.js"></script>
|
||
<script src="../package/new/react-dom.development.js"></script>
|
||
<script src="../package/new/babel.min.js"></script>
|
||
</head>
|
||
<body>
|
||
<div id="app"></div>
|
||
<script type="text/babel">
|
||
class Count extends React.Component{
|
||
constructor(props){
|
||
console.log("1-constructor")
|
||
super(props)
|
||
this.state={count:100}
|
||
}
|
||
|
||
add=()=>{
|
||
let {count}=this.state;
|
||
count+=1;
|
||
this.setState({count})
|
||
}
|
||
death=()=>{
|
||
ReactDOM.unmountComponentAtNode(document.getElementById('app'))
|
||
}
|
||
// 强制更新不受shouldComponentUpdate控制
|
||
force=()=>{
|
||
this.forceUpdate()
|
||
}
|
||
// 定义在类自身，接收props state两个参数，必须返回状态对象
|
||
// 返回状态对象后会劫持原有state state的值在任何时候都取决于props
|
||
static getDerivedStateFromProps(props,state){
|
||
console.log(props,state)
|
||
return props
|
||
}
|
||
render(){
|
||
console.log("3-render")
|
||
return (
|
||
<div>
|
||
<h2>当前求和为：{this.state.count}</h2>
|
||
<button onClick={this.add}>点我+1</button>
|
||
<button onClick={this.death}>销毁</button>
|
||
<button onClick={this.force}>强制更新</button>
|
||
</div>
|
||
)
|
||
}
|
||
componentDidMount(){
|
||
console.log('4-componentDidMount')
|
||
}
|
||
componentWillUnmount(){
|
||
console.log("5-componentWillUnmount")
|
||
}
|
||
// 控制组件更新的阀门
|
||
shouldComponentUpdate(){
|
||
console.log('shouldComponentUpdate')
|
||
return true
|
||
}
|
||
|
||
componentDidUpdate(){
|
||
console.log('componentDidUpdate')
|
||
}
|
||
}
|
||
ReactDOM.render(
|
||
<Count count={1999} />,document.getElementById('app')
|
||
)
|
||
</script>
|
||
</body>
|
||
</html> |