javascript - 为什么两个 JS 日期对象实例化不同？

Question

我想启用/禁用基于日期选择器的按钮，并且我有一个这样的检查设置:

  public dateChanged = false;
  public availableFromDate: Date;
  public availableToDate: Date;

 initDatepickers() {
    const currentDay = new Date();
    this.availableFromDate = currentDay;
    this.availableToDate = currentDay;
  }

 private dateCheck() {
    if ((this.availableFromDate > this.availableToDate) || (this.availableFromDate === this.availableToDate)) {
      this.dateChanged = false;
    } else {
      this.dateChanged = true;
    }
    console.log(this.dateChanged);
    console.log(`Available from - ${this.availableFromDate}`);
    console.log(`Available to - ${this.availableToDate}`);
  }

向上检查效果很好，但是当开始日期较低时启用按钮! 如果您将值记录到控制台，则按钮会被禁用，因为初始值为 false，而不是因为检查有效。

两个日期对象的初始化不同(console.log 转储):

true
clinics-upload-documents.component.ts:73 Available from - Fri Feb 22 2019 00:00:00 GMT+0100 (Central European Standard Time)
clinics-upload-documents.component.ts:74 Available to - Fri Feb 22 2019 10:52:31 GMT+0100 (Central European Standard Time)

它永远不会是假的，因为第一个日期 obj 是 @ 0:00:00，但是第二个日期与当前本地时间相关。

这些用于操作日期:

onFromChange(fromDate) {
  const dateType = 'from';
  this.setDateValues(fromDate, dateType);
}
onToChange(toDate) {
  const dateType = 'to';
  this.setDateValues(toDate, dateType);
}
private setDateValues(date: Date, dateType: string) {
  dateType === 'from' ? this.availableFromDate = new Date(date) : this.availableToDate = new Date(date);
  this.dateCheck();
}

我错过了什么？

Answer 1

改变这个:

const currentDay = new Date();
this.availableFromDate = currentDay;
this.availableToDate = currentDay;

对此:

const currentDay = new Date();
currentDay.setHours(0, 0, 0, 0);
this.availableFromDate = new Date(currentDay);
this.availableToDate = new Date(currentDay);

这会将时间部分归零并直接进行日期比较。

接下来，改变这个:

if (
   (this.availableFromDate > this.availableToDate) ||
   (this.availableFromDate === this.availableToDate)
)

为此(假设您要检查大于或等于):

if (this.availableFromDate >= this.availableToDate)

你 cannot compare two dates with === 尽管您可以使用 < <= >= > 来比较它们.