在 componentWillUpdate 或 componentDidUpdate 中重复调用 setState。 React 限制嵌套更新的数量以防止无限循环

Question

componentDidUpdate(prevProps, prevState) {
const { data } = this.state;

if (prevState.data.date !== data.date) {
  const startDate = new Date(data.date.startDate);
  const endDate = new Date(data.date.endDate);
  const countDuration = new Date(endDate - startDate).getDate();
  this.setState({
    data: {
      ...this.state.data,
      duration: countDuration,
    },
  });
}

if (prevState.data.duration !== data.duration) {
  const startDate = new Date(data.date.startDate);
  const endDate = new Date(
    startDate.setDate(startDate.getDate() + +data.duration - 1)
  );
  this.setState({
    ...this.state,
    data: {
      ...this.state.data,
      date: {
        ...this.state.data.date,
        endDate: endDate,
      },
    },
  });
}

}

But this gives me error, saying Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate. React limits the number of nested updates to prevent infinite loops.

Answer 1

It looks like you're changing the data.date and data.duration properties in the wrong place. As a result, the conditions prevState.data.date.== data.date and prevState.data.duration.== data.duration are never evaluating to true and thus the setState calls happen each time, causing an infinite loop