// 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" />

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>
        </>
        )
    }
}

export default class MyComponent extends React.Component {

onSubmit(e) {
    e.preventDefault();
    var title = this.title.value; //added .value
    console.log(title);
}

render(){
    return (
        ...
        <form className="form-horizontal">
            ...
            <input type="text" className="form-control" ref={input => this.title = input} name="title" />
            ...
        </form>
        ...
        <button type="button" onClick={this.onSubmit} className="btn">Save</button>
        ...
    );
}

};

使用不受控字段:

export default class MyComponent extends React.Component {

    onSubmit(e) {
        e.preventDefault();
        console.log(e.target.neededField.value);
    }

    render(){
        return (
            ...
            <form onSubmit={this.onSubmit} className="form-horizontal">
                ...
                <input type="text" name="neededField" className="form-control" ref={(c) => this.title = c}/>
                ...
            </form>
            ...
            <button type="button" className="btn">Save</button>
            ...
        );
    }

};

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)

你可以在不添加“onChange”函数的情况下获得输入值。

只需在输入元素中添加一个'ref attr:

然后用这个。引用以在需要时获取输入值。