在React JS中应用的页面，如何使用javascript触发onchange

https://codingdict.com/questions/77442

https://codepen.io/catthr/pen/pddWzo

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

    this.handleChange = this.handleChange.bind(this);
    this.handleSubmit = this.handleSubmit.bind(this);
  }

  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>
    );
  }
}

ReactDOM.render(
  <div><NameForm /> <NameForm /> </div>,
  document.getElementById('root')
);

//  doesn't work since v15.6.0
var ev = new Event('input', { bubbles: true});
document.querySelector('form:first-child input').value = 'Not working';
document.querySelector('form:first-child input').dispatchEvent(ev);

var input = document.querySelector('form:last-child input');
var nativeInputValueSetter = Object.getOwnPropertyDescriptor(window.HTMLInputElement.prototype, "value").set;
nativeInputValueSetter.call(input, 'React 16 value');
var ev2 = new Event('input', { bubbles: true});
input.dispatchEvent(ev2);

对于React 16和React > = 15.6

设置.value=器无法正常工作，因为React库会覆盖输入值设置器，但是我们可以直接在inputas上下文中调用该函数。

var nativeInputValueSetter = Object.getOwnPropertyDescriptor(window.HTMLInputElement.prototype, "value").set;
nativeInputValueSetter.call(input, 'react 16 value');

var ev2 = new Event('input', { bubbles: true});
input.dispatchEvent(ev2);

对于textarea元素，你应该使用prototype的HTMLTextAreaElement类。

仅适用于React <= 15.5的过时答案

有了react-dom ^15.6.0您可以使用simulated标志事件对象的事件经过

var ev = new Event('input', { bubbles: true});
ev.simulated = true;
element.value = 'Something new';
element.dispatchEvent(ev);