使用Moment.js，如何将时刻转换为日期或进行日历日期比较？

Question

If you have a moment which is a datetime.

var d1 = moment();

How do I convert d1 to a date (losing time) so you can do math. I'd like to do..

var d1 = moment(); // convert this to a date.
var d2 = moment(); // convert this to a date.

These should return like this*;

d1.isBefore(d2) // false;
d1.isAfter(d2) // false;
d1.isSame(d2) // true

Footnotes

* assuming d2 didn't occur after the day-rollover

Answer 1

Try

moment().startOf('day')

That will shift the time to midnight (in most cases).

Answer 2

Using the two argument form of momement.js comparisons

I'm not sure of the easiest way to do this in that fashion, but the comparison methods are smarter than that.. This is why the .valueOf overrides weren't sufficient for the library.

d1.isBefore(d2); // same as d1 < d2;

But, the signature is

moment().isBefore(Moment|String|Number|Date|Array, String);

And, the second String argument corresponds to this

Like moment#isAfter and moment#isSame, any of the units of time that are supported for moment#startOf are supported for moment#isBefore. Year, month, week, day, hour, minute, and second.

So simply run the same tests like this..

d1.isBefore(d2, 'day') // false;
d1.isAfter(d2, 'day')  // false;
d1.isSame(d2, 'day')   // true