javascript - 在构造函数中初始化状态时出现意外标记

Question

当我尝试在组件中初始化状态时，它会给我 SyntaxError:

处的意外标记

   constructor(props) {
    super(props);

    this.state = {
      isFromDatePicked = false,
      isToDatePicked = false,
      markedDates = {},
    }
  }

isFromDatePicked = false 行。我还尝试在构造函数之外初始化状态，但也根本不起作用。

此外，当我删除状态初始化以测试代码时，它会给我同样的错误

 let markedDates = { ...this.state.markedDates };
      let [_markedDates, range] = this.setupMarkedDates(this.state.fromDate, this.state.toDate, markedDates);
      if (range >= 0) {
        this.setState({ isFromDatePicked: true, isToDatePicked: true, markedDates = _markedDates }); 

markedDates = _markedDates 行。

我不知道为什么会抛出这样的错误。任何帮助将不胜感激，谢谢。

Answer 1

在 {} 中使用 : 而不是 =。来自Object initializer

However, the advantage of the literal or initializer notation is, that you are able to quickly create objects with properties inside the curly braces. You simply notate a list of key: value pairs delimited by comma

在 state 之前也使用 this

constructor(props) {
    super(props);

    this.state = {
      isFromDatePicked:false,
      isToDatePicked:false,
      markedDates:{},
    }
  }

而且在 setState 中，您正在传递一个对象，因此请使用 : 而不是 =

this.setState({ isFromDatePicked: true, isToDatePicked: true, markedDates :_markedDates });