如何在不更改日期内容的情况下更改日期的时区？

Question

We are working with another company that builds the back, and they are saving the date in this format:

"2020-12-12T12:00:00.0000Z"

The thing is, when we create a Date object passing that date, it adds 2 hours to it (as we are in GMT+2), so when we try to compare to the current date it's never the same.

So what we need is to transform that date to GMT+2 so we can compare dates, but without modifying the date it's initially displaying.

Answer 1

... it adds 2 hours to it...

No, it doesn't. It gives you a Date representing the time the string defines. The string has the Z suffix meaning it's expressed in GMT/UTC. If you parse that, the result is a Date object that represents that moment in time. In your timezone, the timezone-sensitive functions ( getHours , getMinutes , toString ) will use your timezone to provide appropriate values. The UTC functions ( getUTCHours , getUTCMinutes , toUTCString ) will use UTC (GMT).

If the backend is sending you that string and it's not meant to be in UTC, then the backend is sending you an incorrect string.

If you wanted to ignore the timezone indicator on the string and parse it as though it were local time, your best bet would be to break it into parts and use the new Date(year, month, day) constructor. However, you could also just remove the Z , as the specification says that date/time forms without a timezone indicator are parsed in local time (whereas date-only is UTC). The spec moved around a bit on this, though, which is why I suggest using the new Date(year, month, day) constructor instead.

Answer 2

Try to add moment for this purpose npm install moment-timezone --save

And in your code

var a = moment.tz("2020-12-12T12:00:00.0000Z", "Asia/Taipei");
a.format(); // 2020-12-12T12:55:00+08:00

Your zone for exmaple = Asia/Taipei

Hope useful