So erhalten Sie den Wert der Eingabe in React

<input onChange={(e)=>this.inputChange(e)}/>
<button onClick={()=>this.getInputValue} >获取input的值</button>
inputChange(e){
alert(e.target.value)
this.setState({
username:e.target.value
})
}
getInputValue(){
alert(this.state.username)
}

<input ref=&#39;username&#39; onChange={()=>this.inputChange()}/>
<button onClick={()=>this.getInputValue()} >获取input的值</button>
inputChange(){
//获取dom节点元素
//1.添加ref属性
//2.使用this.refs.username获取dom节点
let val=this.refs.username.value;
this.setState({
username:val
})
}
getInputValue(){
console.log(this.state.username)
}