Get timezone offset from timezone name using Javascript

Question

I found many solution that gives Timezone name from offset value. But I have Timezone name and I want offset value for that. I tried setTimezone('Asia/Kolkata'), but I think their is no method like setTimezone.

example:

Asia/Kolkata should give me -330 ( offset )

Let me see if i've understood your siutation. You have a timezeon A and you want to get the time difference between other timezone B. My questión is... your variable are the two timezones, hence both time zone will be changer often? or only one of this timezone may change, for example there is a client with a timezone and you just one to know the time difference from the client to your server? — user688877, Jan 24 '14 at 11:40
only one timezone will change...Server's timezone is fix it's UTC 0. When client timezone is Asia/Kolkata in that case I want offset of that timezone (means -330 minutes ). — Hardik Sondagar, Jan 25 '14 at 09:49

score 8 · Answer 1 · answered Jul 30 '21 at 15:10

This has got the be the easiest way to accomplish this task with modern JavaScript.

Note: Keep in mind that the offset is dependent on whether Daylight Savings Time (DST) is active.

/* @return A timezone offset in minutes */
const getOffset = (timeZone = 'UTC', date = new Date()) => {
  const utcDate = new Date(date.toLocaleString('en-US', { timeZone: 'UTC' }));
  const tzDate = new Date(date.toLocaleString('en-US', { timeZone }));
  return (tzDate.getTime() - utcDate.getTime()) / 6e4;
}

console.log(`No arguments: ${getOffset()}`); // 0

{
  console.log('! Test Case #1 >> Now');
  console.log(`Asia/Colombo     : ${getOffset('Asia/Colombo')}`);     //  330
  console.log(`America/New_York : ${getOffset('America/New_York')}`); // -240
}

{
  console.log('! Test Case #2 >> DST : off');
  const date = new Date(2021, 0, 1);
  console.log(`Asia/Colombo     : ${getOffset('Asia/Colombo', date)}`);     //  330
  console.log(`America/New_York : ${getOffset('America/New_York', date)}`); // -300
}

{
  console.log('! Test Case #3 >> DST : on');
  const date = new Date(2021, 5, 1);
  console.log(`Asia/Colombo     : ${getOffset('Asia/Colombo', date)}`);     //  330
  console.log(`America/New_York : ${getOffset('America/New_York', date)}`); // -240
}

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score 4 · Answer 2 · answered Mar 31 '21 at 22:54

I came across this same issue, and this is the solution I came up with, if you can get an IANA tz database name like the one you mentioned:

var myTimezoneName = "Asia/Colombo";
 
// Generating the formatted text
var options = {timeZone: myTimezoneName, timeZoneName: "short"};
var dateText = Intl.DateTimeFormat([], options).format(new Date);
 
// Scraping the numbers we want from the text
var timezoneString = dateText.split(" ")[1].slice(3);

// Getting the offset
var timezoneOffset = parseInt(timezoneString.split(':')[0])*60;

// Checking for a minutes offset and adding if appropriate
if (timezoneString.includes(":")) {
    var timezoneOffset = timezoneOffset + parseInt(timezoneString.split(':')[1]);
}

It's not a very nice solution, but it does the job without importing anything. It relies on the output format of the Intl.DateTimeFormat being consistent, which it should be, but that's a potential caveat.

Thank you! After much searching, I finally found my answer here. Much appreciated. — Armando, Jul 01 '21 at 12:48
Note, it won't always work because in "short" format some timezones are represented by their name like "PST" rather than their offset. The better approach would be to print timezone in "shortOffset" format, but this option is not supported in Node.js. — Alexander Korostin, Jan 16 '22 at 21:43

score 3 · Answer 3 · edited May 23 '17 at 11:44

3

You can't get it by name alone. You would also need to know the specific time. Asia/Kolkata may be fixed to a single offset, but many time zones alternate between standard time and daylight saving time, so you can't just get the offset, you can only get an offset.

For how to do it in JavaScript, see this answer.

edited May 23 '17 at 11:44

Community

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answered Jan 24 '14 at 21:47

Matt Johnson-Pint

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Nathan Dullea · Answer 4 · 2020-04-03T20:24:44.633

Using countries and timezones npm package:

import {getTimezone} from 'countries-and-timezones';
const australianTimezone = 'Australia/Melbourne';
console.log(getTimezone(australianTimezone));

Prints to the console:

{
  name: 'Australia/Melbourne',
  country: 'AU',
  utcOffset: 600,
  utcOffsetStr: '+10:00',
  dstOffset: 660,
  dstOffsetStr: '+11:00',
  aliasOf: null
}

From there, you can use the utcOffset or dstOffset depending on if it is daylight savings time.

Get timezone offset from timezone name using Javascript

4 Answers4

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