Question

我目前正在与“无法在未安装的组件错误上使用setState（）或forceUpdate（）”作斗争，并且很难跟踪错误来自哪个异步操作。我怀疑是因为我使用setInterval添加秒来显示当前时间。这是我在componentDidMount，componentWillUpdate和componentWillUnmount中负责管理时间显示的内容：

componentDidMount() {
    this.mounted = true;

    //listener to identify whether app is active/inactive
    AppState.addEventListener('change', this.handleAppStateChange.bind(this));

    //get user's intranet schedule
    this.props.actionsMain.getSchedule(this.props.staff.staffID);

    this.getLocation();
    //After the first location received, re-check every 20 seconds
    this.locationInterval = setInterval(() => {
      this.getLocation();
    }, 20000);
  }

componentDidUpdate() {
    //when we just received server time, parse and set the time to state, then set the interval timer
    if (this.props.scheduleReceived && this.state.time[0] === null) {
      let time = this.props.schedule['time_server'].split(':'),
        hh = parseInt(time[0]) + this.props.location.zone,
        mm = parseInt(time[1]),
        ss = parseInt(time[2]);

      if (this.mounted) {
        this.setState({ time: [hh, mm, ss] });

        this.serverTimeInterval = setInterval(() => {
          let { time } = this.state, hh = time[0], mm = time[1], ss = time[2];

          //add second and adjust time
          ss += 1;
          if (ss >= 60) {
            ss -= 60;
            mm += 1;

            if (mm >= 60) {
              mm -= 60;
              hh += 1;

              if (hh >= 24)
                hh -= 24;
            }
          }

          if (this.mounted)
            this.setState({ time: [hh, mm, ss] })
        }, 1000)
      }
    }
  }

componentWillUnmount() {
    //Remove all timer events
    clearInterval(this.serverTimeInterval);
    clearInterval(this.locationInterval);

    //Remove listener
    AppState.removeEventListener('change', this.handleAppStateChange.bind(this));

    this.mounted = false;
  }

任何人都可以指出我在这里做错了什么，即使我正在做的事情也是一种很好的做法吗？

同样，我的第二个怀疑来自提取位置承诺，该承诺是从setInterval()执行并返回到未安装的组件的。如果有任何经验法则可以遵循，我将如何确保setInterval，setState和Promises和谐地工作，那真是太棒了！

谢谢！

Answer 1

永远不要在componentDidUpdate中调用setState，否则会导致无限循环

React Native：使用setState设置setInterval和Promises的最佳实践

1 个答案: