javascript - 卸载组件时对 setState 发出警告

Question

当我执行以下代码(参见下面的代码片段)时，我收到警告:

Warning: setState(...): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op. Please check the code for the Blinker component.

我的 Mounter 类下的 componentWillUnmount() 方法是否做错了什么？谢谢!

class Blinker extends React.Component {
   constructor(props) {
    super();
    this.state = {
      appear: true
    }
    this.blinker = this.blinker.bind(this);
  }

  blinker()  {
    this.setState({appear: !this.state.appear });
  }

  componentDidMount() {
    setInterval(this.blinker, 300)
  }

  render() {
    return (
      <div>
        { (this.state.appear) && "xxx" }
      </div>
    );
  }
}

class Mounter extends React.Component {
  constructor(props) {
    super();
    this.state = {
      render: true
    };
    this.interval = null;
  }

  componentDidMount() {
    this.interval = setTimeout( () =>
      this.rendering(), 1500
    );
  }

  componentWillUnmount() {
    clearInterval(this.interval);
  }

  rendering() {
    this.setState({ render: !this.state.render });
  }

  render() {
    return (
      <div>
        <h1>
          { this.state.render && <Blinker /> }
        </h1>
      </div>
    );
  }   
}



ReactDOM.render(<Mounter />, app);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>

<div id="app"></div>

Answer 1

清除this.interval并在设置状态之前检查它。这将防止组件卸载后设置状态。

componentWillUnmount() {
  clearInterval(this.interval);
  this.interval = null; // clear
}

rendering() {
  // this.interval will be null when unmounting so avoid setting state:
  if (this.interval) {
    this.setState({
      render: !this.state.render
    });
  }
}