// On the state
constructor() {
  this.state = {
   email: ''
 }
}

// Input view ( always check if property is available in state {this.state.email ? this.state.email : ''}

<Input 
  value={this.state.email ? this.state.email : ''} 
  onChange={event => this.setState({ email: event.target.value)}
  type="text" 
  name="emailAddress" 
  placeholder="johdoe@somewhere.com" />

在功能组件中:-

export default function App(){

const [state, setState] = useState({
        value:'',
        show:''
    });

const handleChange = (e) => {
    setState({value: e.target.value})
}

const submit = () => {
    setState({show: state.value})
}

return(
        <>
            <form onSubmit={()=>submit()}>
                <input type="text" value={state.value} onChange={(e)=>handleChange(e)} />
                <input type="submit" />
            </form>
            <h2>{state.show}</h2>
        </>
)}

你应该在MyComponent extends React类下使用构造函数。组件

constructor(props){
    super(props);
    this.onSubmit = this.onSubmit.bind(this);
  }

然后你会得到标题的结果

将ref='title'更改为:ref='title'并删除name='title' 然后删除var title = this。标题和写作:

console.log(this.refs.title.value)

此外，你应该添加.bind(this)到this. onsubmit

(它在我的情况下工作，这是非常相似的，但不是onClick，我有onSubmit={…}，它被放在form (<form onSubmit={…} > < / >形式)

在react 16中，我使用

<Input id="number" 
       type="time" 
       onChange={(evt) => { console.log(evt.target.value); }} />

export default class App extends React.Component{
     state={
         value:'',
         show:''
      }

handleChange=(e)=>{
  this.setState({value:e.target.value})
}

submit=()=>{
   this.setState({show:this.state.value})
}

render(){
    return(
        <>
          <form onSubmit={this.submit}>
             <input type="text" value={this.state.value} onChange={this.handleChange} />
             <input type="submit" />
          </form>
          <h2>{this.state.show}</h2>
        </>
        )
    }
}