How to create time in a specific time zone with mo

问题:

I have this backend that sends me a pre formatted time in a set time zone, but without any information for the said time zone. The strings are like: "2013-08-26 16:55:00".

I can create a new moment.js instance with this string:

var time = moment("2013-08-26 16:55:00") //this creates time in my tz

but this will only create an instance in my own time zone.

Moment.js have a plugin that can create instances of the object in specific time zones and it works great, but I can't say what time I want the object to point to.

If I'm in New York and I do this:

var time = moment("2013-08-26 16:55:00").tz("America/Los_Angeles");

the resulting time will be 13:55 instead of 16:55 but in LA.

What I want is to create an instance that will say 16:55, but in LA time.

The reason I'm asking is because I want to do this:

var now = moment.tz("America/Los_Angeles");
var end = moment("2013-08-26 16:55:00"); //plus something to convert LA time

var timeLeft = end.diff(now, "minutes");

Is there a way to do that?

回答1:

In most cases, you can simply do this:

moment.tz("2013-08-26 16:55:00", "America/Los_Angeles")

If you require input other than ISO8601, then specify the format string as the second parameter, and the time zone as the third:

moment.tz("8/26/2013 4:55 pm", "M/D/YYYY h:mm a", "America/Los_Angeles")

And if you need to use moment's "strict parsing" mode, then that goes in the third parameter, and the time zone moves to the fourth position:

moment.tz("8/26/2013 4:55 pm", "M/D/YYYY h:mm a", true, "America/Los_Angeles")

回答2:

If you want to calculate everything in a specific timezone you want to set the default time zone using

A) moment.tz.setDefault("America/Los_Angeles");

For my use case (in a node.js project) I just set it right after requiring the moment modules like so:

let moment = require('moment');
require('moment-timezone');
moment.tz.setDefault("America/Los_Angeles");

All calls to moment() thereafter will create the time in the "America/Los_Angeles" setting, which is NOT the same as using:

B) moment.tz("2017-03-04 00:00", "America/Los_Angeles")

OR

C) moment("2017-03-04 00:00").tz("America/Los_Angeles")

both of which would create the moment object in UTC time (unless you already changed the default), and then convert it to be the Los Angeles timezone.

Running B or C above in the browser console yields:

_d: Fri Mar 03 2017 16:00:00 GMT-0800 (PST)
_i: "2017-3-4 00:00"

Notice _d shows March 3 4:00pm; this is because the moment object is created with March 4 12:00am in UTC time, then converted to Pacific timezone, which is 8 hours behind/the previous day.

source: http://momentjs.com/timezone/docs/#/using-timezones/default-timezone/