从外部触发时无法更新 React 组件状态

Question

我对 React 比较陌生，还没有在网上找到解决方案。我的代码：

const socketPlay = () => {
  socket.emit("playing", true);
}

const socketStop = () => {
  socket.emit("playing", false);
}

class App extends Component {
  state = {
    playing: false,
    url: 'XXXX',
  }
  
  handlePlay = () => {
    this.setState({ playing: true });
    socketPlay();
  }

  handlePause = () => {
    this.setState({ playing: false })
    socketStop();
  }

  ref = player => {
    this.player = player
  }

  render() {
    const { url, playing, controls, light, volume, muted, loop, played, loaded, duration, playbackRate, pip } = this.state
    const SEPARATOR = ' · '
    return (
      <ReactPlayer
        ref={this.ref}
        className='react-player'
        width='40%'
        playing={playing}
        onPlay={this.handlePlay}     
        onPause={this.handlePause}
      />
    )
  }
}
export default App;

const app = new App();

socket.on("toClient", (args) => {
  console.log("from server: " + args);
  switch (args) {
    case true:
      app.handlePlay();
      break;
    case false:
      app.handlePause();
      break;
    default:
      break;
  }
});

当我通过浏览器 handlePlay() 与组件交互时，正确设置了状态“playing: true”。如果通过 app.handlePlay() 在组件外部调用它，则状态保持为“正在播放：false”。

app.handlePlay() 得到正确执行。只有 this.setState 不工作。浏览器控制台抛出“警告：无法在尚未安装的组件上调用 setState。”

非常感谢您的帮助。提前致谢，一月

Answer 1

查看您的代码，在我看来，使用 componentDidMount[=14= 在 App Class 中添加 socket.on("toClient", 侦听器会更容易]

class App extends Component {
  state = {
    playing: false,
    url: 'XXXX',
  }
  componentDidMount(){ 
    socket.on("toClient", (args) => {
    console.log("from server: " + args);
    switch (args) {
    case true:
      this.handlePlay();
      break;
    case false:
      this.handlePause();
      break;
    default:
      break;
  }
});
}

  
  handlePlay = () => {
    this.setState({ playing: true });
    socketPlay();
  }

  handlePause = () => {
    this.setState({ playing: false })
    socketStop();
  }

  ref = player => {
    this.player = player
  }

  render() {
    const { url, playing, controls, light, volume, muted, loop, played, loaded, duration, playbackRate, pip } = this.state
    const SEPARATOR = ' · '
    return (
      <ReactPlayer
        ref={this.ref}
        className='react-player'
        width='40%'
        playing={playing}
        onPlay={this.handlePlay}     
        onPause={this.handlePause}
      />
    )
  }
}
export default App;

从外部触发时无法更新 React 组件状态

Can't update React Component state when triggered from outside

javascript

reactjs

socket.io

react-hooks

react-component