Moment.Js: Offsetting dates using UTC and Timezone

Question

I am trying to adjust a time using a timezone offset and a UTC timestamp.

I am running the following code:

var date = {
    utc: '2013-10-16T21:31:51',
    offset: -480
}

var returnDate = moment(date.utc).utc().zone(date.offset).format('MM/DD/YYYY h:mm A');

What I am expecting is: 10/16/2013 1:31 PM but I am ending up with 10/17/2013 9:31 AM

Answer 1

I use the jsTimezoneDetect library to determine the timezone name instead of the offset.

Then use this on a UTC timestamp:

timestamp = moment.tz(timestamp, tz.name());
timestamp.format('MM/DD/YYYY h:mm A');

Answer 2

Here is what worked for me:

var date = {
  utc: '2013-10-16T21:31:51',
  offset: 480
}

var returnDate = moment.utc(date.utc).zone(date.offset).format('MM/DD/YYYY h:mm A');

If you noticed, I changed the offset to a positive number. This gave the desired result. If the offset was left at -480 the output was 10/17/2013 5:31 AM.

There is a moment#UTC method that initializes the date as UTC vs. local time.