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How to convert a UTC time to local time javascript

I have a requirement to convert a UTC time local time based on user timezone
I have two parameters utc time and users timezone as a string
ie
0,1,2,3 ...12 (timezone)
0,-1,-2,-3 ...-12 (timezone)
var utc = "2014-10-18T06:14:41.512Z"
tz = 5.5(Indian Standard Time)
Expected result Sat Oct 18 2014 11:44:28 GMT+0530
I have tried moment js
moment("2014-10-18T06:14:41.512Z").zone('+05:30').format('YYYY-MM-DD HH:mm')
and the result is correct.
But when i change the timezone to other it is not showing as expected result
tried
moment("2014-10-18T06:14:41.512Z").zone('+12:00').format('YYYY-MM-DD HH:mm')
result "2014-10-18 18:14" Expected 2014-10-18 19:18
12 is NewZeland timezone. Please help me to solve this issue. Thank you

Check this
var date = new Date('2014-10-19 17:00:34 UTC');
date.toString();
var timezone = "America/New_York";
var utcDate = "2014-10-19T10:31:59.0537721Z";
var localDate = moment.utc(utcDate).tz(timezone).format()
Also check
http://www.digitoffee.com/programming/get-local-time-utc-using-moment-js/94/

To adhere to international standards, you need to format your UTC date to include the time delimiter T, and the zone designator Z.
Z is the timezone designator for the zero UTC offset aka Zulu time.
You can read more about the International Date Standard ISO8601 format specifics here.
Once you've conformed to the international standard, the cross browser friendly approach is simple:
new Date('2014-10-19T17:00:34Z');
// Sun Oct 19 2014 12:00:34 GMT-0500 (Central Daylight Time)

A time zone is not an offset. An offset is only part of a time zone. Many time zones alternate between two different offsets to account for daylight saving time. The time zone has to account for this, including the specific dates and times that daylight saving time begins and ends, as well as any history of changes that the time zone may have had.
The New Zealand case you gave is a perfect example. You said "12 is New Zealand timezone", and thus expected since New Zealand is in DST for that date that the conversion from 6:14 UTC to New Zealand local time would be 19:14. - 13 hours later.
But 12 doesn't fully represent New Zealand. It is just a 12 hour offset from UTC. There are plenty of other time zones that use the same offset in different ways. For example, the Marshal Islands use UTC+12 year round, without daylight saving time.
You should really read the timezone tag wiki - especially the section titled "Time Zone != Offset".
Instead of offsets, you should represent time zones with their full IANA identifier from the tz database. For example US Eastern Time is "America/New_York", Indian Time is "Asia/Kolkata", and New Zealand Time is "Pacific/Auckland". You can find more in the list on Wikipedia.
You can use moment-timezone to work with these in JavaScript.
moment("2014-10-18T06:14:41.512Z").tz('Pacific/Auckland').format('YYYY-MM-DD HH:mm')
// Output: "2014-10-18 19:14"
I also cover these topics in great detail in my Date and Time Fundamentals course on Pluralsight.com.

Please Check this link
http://www.digitoffee.com/programming/get-local-time-utc-using-moment-js/94/
var timezone = "UTC+5.30";
var utcDate = "2014-10-19T10:31:59.0537721Z";
var localDate = moment.utc(utcDate).tz(timezone).format()

Parse JavaScript Date in local time zone

I'm trying to parse the value of a datetime-local input so the format is 'yyyy-mm-ddTHH:mm'. I want the assumption to be that I'm parsing in the local time zone of the user, i.e. if they enter 09:00 they mean 9am in their time zone.
Also not just the current time offset, e.g. if the user enters a date in June then they mean daylight savings time regardless of the fact it's now November and DST has ended.
I've tried using regular Date objects and moment.js but the assumption is always that the time zone is UTC.
Is there a way to do this?

// dateString is the value from datetime-local
var dateInLocal = moment(dateString, "YYYY-MM-DDThh:mm");

How to create time in a specific time zone with moment.js

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?

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")

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/

install moment-timezone
> npm install moment-timezone
Or see https://momentjs.com/timezone/docs/
.tz(string, string)
moment.tz("2020-01-02 13:33:37", "Iran/Tehran")

Just to make something abundantly clear, that is implied in other answers but not really stated:
You absolutely must either
use ISO8601 as your date format or
specify the format your string is in
.. when using the .tz(string datetime, [string format,] string zone) function, if you want moment to interpret the datetime argument you give to be in the zone you give. If you omit format, be sure to pass an ISO8601 formatted string
For 2 days I went round in circles, because my API was delivering a time string like "03 Feb 2021 15:00" and sure, it parsed OK, but it always used the timezone from my local machine, then converted to the timezone I gave:
//this always resulted in "2021-02-03 10:00 EST" if run on a machine in UTC
moment.tz("03 Feb 2021 15:00", "America/Indianapolis").format("YYYY-MM-DD HH:mm z")
This was massively confusing: the parsing was clearly working fine, because the date was right but the time was always wrong by however many hours there were between the machine and the given zone string
Switching to ISO format input worked:
//this always resulted in "2021-02-03 15:00 EST" if run on a machine in UTC
moment.tz("2021-02-03 15:00", "America/Indianapolis").format("YYYY-MM-DD HH:mm z")
As did declaring:
//this always resulted in "2021-02-03 15:00 EST" if run on a machine in UTC
moment.tz("03 Feb 2021 15:00", "DD MMM YYYY HH:mm", "America/Indianapolis").format("YYYY-MM-DD HH:mm z")
I hope this saves someone some time

I had a similar issue for which i had to use New York based time so i had to consider for daylight savings. I tried using the above few answers but wasn't able to get it working. Then I solved my issue like the below code
import moment from 'moment-timezone'
const time = timestamp
const offset = moment.tz.zone('America/New_York')?.parse(time)
const date = moment(time).add(offset, 'minutes').toISOString()
or you can do this way which will consider the time offset on its own when you display locally.
const time = moment.tz(timestamp, 'America/New_York')
const localtz = moment.tz.guess()
const date = time.clone().tz(localtz)
this gives you an ISO string which you can use as below
moment(date).local().format('dddd, MMM DD YYYY, hh:mm A')
or in whatever format you would like to display it

Converting Unix Timestamp to PST

Hi I have a json which I am getting some data. There the time format I am getting is like
1367023443000
I want to convert this to the Normal PST format. Ive tried using Javascript`s Date method. Passed the Unix time to the Date method,
var now = new Date(1367023443000);
I am getting only IST value, But not PST. What should I do here to convert the Unix timestamp to PST?

If you're not actually in the US Pacific Time zone, the only way to do this reliably in JavaScript is with a library that implements the TZDB database. I list several of them here.
For example, using walltime-js library, you can do the following:
var date = new Date(1367023443000);
var pacific = WallTime.UTCToWallTime(date, "America/Los_Angeles");
var s = pacific.toDateString() + ' ' + pacific.toFormattedTime();
// output: "Fri Apr 26 2013 5:44 PM"
You can't just add or subtract a fixed number, because the target time zone may use a different offset depending on exactly what date you're talking about. This is primarily due to Daylight Saving Time, but also because time zones have changed over time.

What format is this timestamp, and how can I format it in its own time

I have a problem converting a timestamp in javascript.
I have this timestamp:
2011-10-26T12:00:00-04:00
I have been trying to format it to be readable. So far, it converts this using the local time of my system instead of the GMT offset in the timestamp. I know the timezone that this was created in is EST. I'm in PST, so the times are being offset by 3 hours.
Instead of this showing as:
Wednesday October 26, 2011 12:00 pm
It shows as:
Wednesday October 26, 2011 9:00 am
I have tried a few different solutions, but the latest one is found here: http://blog.stevenlevithan.com/archives/date-time-format
I am less concerned with the formatting part as I am with figuring out how to handle the GMT offsets. Would appreciate any help and insight anyone can provide.

Date objects are created in the local zone. If the date string was created in a different time zone, then you need to adjust the date object to allow for the difference.
The abbreviations PST and EST are ambiguous on the web, there is no standard for time zone abbreviations and some represent two or zones. You should express your zone only in terms of +/- UTC or GMT (which are the same thing, more or less).
You can get the local time zone offset using Date.prototype.getTimezoneOffset, which returns the offset in minutes that must be added to a local time to get UTC. Calculate the offset for where the time string was created and apply it to the created date object (simply add or subtract the difference in minutes as appropriate).
If your time zone is -3hrs, getTimezoneOffset will return +180 for a date object created in that zone. If the string is from a zone -4hrs, its offset is +240. So you can do:
var localDate = new Date('2011-10-26T12:00:00') // date from string;
var originOffset = 240;
var localOffset = localDate.getTimezoneOffset();
localDate.setMinutes( localDate.getMinutes() + originOffset - localOffset );
Adding the origin offset sets it to UTC, subracting the local offset sets it to local time.
It would be much easier if the time string that was sent by the server was in UTC, that way you just apply the local offset.
Edit
IE will not parse a time string with an offset, and Chrome thinks that the above time string is UTC and adjusts for local offset. So don't let Date parse the string, do it manually.

It doesn't matter what time zone you are- the time stamp will result in a different local time for every different time-zone, but they all will be correct, and anyone checking the UTC time of the date will get the same time-stamp:
new Date('2011-10-26T12:00:00-04:00').toUTCString()
returns
Wed, 26 Oct 2011 16:00:00 GMT
and getTime() anywhere returns the same milliseconds universal timestamp:1319644800000