React三大属性之Refs的使用详解

//直接定义refs,已废弃
class App extends React.PureComponent{
    changeInput = ()=>{
        const {input} = this.refs
    }
    render() {
        return (
            <div>
                <input type="text" placeholder={"please input your value"} onBlur={this.changeInput} ref={"input"}/>
            </div>
        )
    }
}

//用回调的形式使用
class App extends React.PureComponent{
    changeInput = ()=>{
        console.log(this.inputRef);
    }
    render() {
        return (
            <div>
                <input type="text" placeholder={"please input your value"} onBlur={this.changeInput} ref={(el)=>{this.inputRef = el}}/>
            </div>
        )
    }
}

//用createRef
class App extends React.PureComponent{
    inputRef = React.createRef()
    changeInput = ()=>{
        console.log(this.inputRef.current);
    }
    render() {
        return (
            <div>
                <input type="text" placeholder={"please input your value"} onBlur={this.changeInput} ref={this.inputRef}/>
            </div>
        )
    }
}

function App(){
    const inputRef = useRef("")
    return (
        <div>
            <input type="text" placeholder={"please input your value"} ref={inputRef}/>
        </div>
    )
}