问如何在单击复选框时将一个输入框复制到另一个输入框

EN

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      BillingAddress: "",
      ShippingAddress: "",
      copybilling: false
    };
  }

  changeDetails = e => {
    const { name, value, checked, maxLength } = e.target;
    const { Details, formErrors } = this.state;
    let formObj = {};
    if (name === "copybilling") {
      // handle the change event of language field
      if (checked) {
        // push selected value in list
        this.setState({
          [name]: true,
          ShippingAddress: this.state.BillingAddress
        });
      } else {
        // remove unchecked value from the list
        this.setState({
          [name]: false,
          ShippingAddress: ''
        });
      }
    } else {
      // handle change event except language field
      this.setState({
        [name]: value
      });
    }
  };

  render() {
    return (
      <div>
        <textarea
          name="BillingAddress"
          value={this.state.BillingAddress}
          onChange={this.changeDetails}
        />
        <textarea
          name="ShippingAddress"
          value={this.state.ShippingAddress}
          onChange={this.changeDetails}
        />
        Copy :
        <input
          type="checkbox"
          name="copybilling"
          checked={this.state.copybilling}
          onChange={this.changeDetails}
        />
      </div>
    );
  }
}

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

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="root"></div>