受控组件

表单组件的值来自state

class NameForm extends React.Component {
  constructor(props) {
    super(props);
    this.state = {value: ''};
  }

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

  handleSubmit = (event) => {
    alert('A name was submitted: ' + this.state.value);
    event.preventDefault();
  }

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <label>
          Name:
          <input type="text" value={this.state.value} onChange={this.handleChange} />
        </label>
        <input type="submit" value="Submit" />
      </form>
    );
  }
}

非受控组件

表单组件的值来自DOM

class NameForm extends React.Component {
  constructor(props) {
    super(props);
    this.input = React.createRef();
  }

  handleSubmit= (event) => {
    alert('A name was submitted: ' + this.input.current.value);
    event.preventDefault();
  }

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <label>
          Name:
          <input type="text" ref={this.input} />
        </label>
        <input type="submit" value="Submit" />
      </form>
    );
  }
}

使用场景

一般情况下使用受控组件

必须手动操作DOM时使用非受控组件.

例如 操作上传组件时

<input type="file" />