Format Date in a Specific Timezone

Format date in a specific timezone

As pointed out in Manto's answer, .utcOffset() is the preferred method as of Moment 2.9.0. This function uses the real offset from UTC, not the reverse offset (e.g., -240 for New York during DST). Offset strings like "+0400" work the same as before:

// always "2013-05-23 00:55"
moment(1369266934311).utcOffset(60).format('YYYY-MM-DD HH:mm')
moment(1369266934311).utcOffset('+0100').format('YYYY-MM-DD HH:mm')

The older .zone() as a setter was deprecated in Moment.js 2.9.0. It accepted a string containing a timezone identifier (e.g., "-0400" or "-04:00" for -4 hours) or a number representing minutes behind UTC (e.g., 240 for New York during DST).

// always "2013-05-23 00:55"
moment(1369266934311).zone(-60).format('YYYY-MM-DD HH:mm')
moment(1369266934311).zone('+0100').format('YYYY-MM-DD HH:mm')

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To work with named timezones instead of numeric offsets, include Moment Timezone and use .tz() instead:

// determines the correct offset for America/Phoenix at the given moment
// always "2013-05-22 16:55"
moment(1369266934311).tz('America/Phoenix').format('YYYY-MM-DD HH:mm')

Convert date to another timezone in JavaScript

Here is the one-liner:

function convertTZ(date, tzString) {
    return new Date((typeof date === "string" ? new Date(date) : date).toLocaleString("en-US", {timeZone: tzString}));   
}

// usage: Asia/Jakarta is GMT+7
convertTZ("2012/04/20 10:10:30 +0000", "Asia/Jakarta") // Tue Apr 20 2012 17:10:30 GMT+0700 (Western Indonesia Time)

// Resulting value is regular Date() object
const convertedDate = convertTZ("2012/04/20 10:10:30 +0000", "Asia/Jakarta") 
convertedDate.getHours(); // 17

// Bonus: You can also put Date object to first arg
const date = new Date()
convertTZ(date, "Asia/Jakarta") // current date-time in jakarta.

   

Convert Date/Time for given Timezone - java

For me, the simplest way to do that is:

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

Calendar calendar = Calendar.getInstance();
calendar.setTime(new Date());
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");

//Here you say to java the initial timezone. This is the secret
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
//Will print in UTC
System.out.println(sdf.format(calendar.getTime()));    

//Here you set to your timezone
sdf.setTimeZone(TimeZone.getDefault());
//Will print on your default Timezone
System.out.println(sdf.format(calendar.getTime()));

Create a Date with a set timezone without using a string representation

using .setUTCHours() it would be possible to actually set dates in UTC-time, which would allow you to use UTC-times throughout the system.

You cannot set it using UTC in the constructor though, unless you specify a date-string.

Using new Date(Date.UTC(year, month, day, hour, minute, second)) you can create a Date-object from a specific UTC time.

Java SimpleDateFormat(yyyy-MM-dd'T'HH:mm:ss'Z') gives timezone as IST

You haven't set the timezone only added a Z to the end of the date/time, so it will look like a GMT date/time but this doesn't change the value.

Set the timezone to GMT and it will be correct.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
sdf.setTimeZone(TimeZone.getTimeZone("GMT"));

How to ISO 8601 format a Date with Timezone Offset in JavaScript?

Here's a simple helper function that will format JS dates for you.

function toIsoString(date) {
  var tzo = -date.getTimezoneOffset(),
      dif = tzo >= 0 ? '+' : '-',
      pad = function(num) {
          return (num < 10 ? '0' : '') + num;
      };

  return date.getFullYear() +
      '-' + pad(date.getMonth() + 1) +
      '-' + pad(date.getDate()) +
      'T' + pad(date.getHours()) +
      ':' + pad(date.getMinutes()) +
      ':' + pad(date.getSeconds()) +
      dif + pad(Math.floor(Math.abs(tzo) / 60)) +
      ':' + pad(Math.abs(tzo) % 60);
}

var dt = new Date();
console.log(toIsoString(dt));

How to convert a Date in specific Timezone and send to server

You've got a few different questions and misconceptions, so I will attempt to address each of them, starting with question in the title:

How to convert a Date in specific Timezone and send to server

• If you mean a date like 2021-01-18, that cannot be in a particular time zone. It is, by definition, just a date. Think about a printed calendar you might hang on your wall that has a square for each date. There are no time zones associated with such calendars. One can ask "what date is it now in a particular time zone", but the answer itself has no time zone.

• If instead you meant a JavaScript Date object, the answer is again "you can't". The Date object is not actually a date, nor does it have a time zone, but rather it is a timestamp. Internally, a Date object only holds one value - the number of milliseconds that have elapsed since 1970-01-01 00:00:00.000 UTC (not considering leap seconds). It has no time zone. Instead, some functions such as .toString() will apply the system-local time zone while operating. That time zone comes from the operating system (in most cases). It is not stored inside the Date object itself.

My scenario is a Date object created using the browser timezone (just using new Date()) ...

That will use the system clock where the browser is running, but the time zone is not relevant. The Date object will be constructed from the Unix timestamp that represents "now". Such timestamps are inherently UTC based. The browser fetches the UTC time directly from the operating system, without considering time zone.

... and sent to the server

One cannot send an object to a server without going through deserialization on one side and serialization on the other.

... but I want to send this date with another specific timezone let's assume it's, Europe/Athens.

What would be the best representation of the actual date string so I can convert it back to a Date object in the backend in the actual Europe/Athens date?

Since the object only represents "now", you don't need to send it in a time zone specific format. Just send the UTC time. The ideal format is ISO 8601, which can be obtained directly using the .toISOString() function from the Date object.

Depending on your use case, you might also consider whether you might instead just take the UTC time from the server instead. At least you will have some control over the clock.

On the server side, if you need the time in a specific time zone, then convert from UTC to that time zone on the server, not on the client.

Also, from comments:

I believe even EPOCH is different between timezones. I could just get the EPOCh and then try to work with converting to specific timezones.

That is incorrect on a few levels. First, understand that epoch is just an English word meaning essentially "a representation of a starting point". It isn't a format, nor is it an acronym. In JavaScript, Date objects use Unix timestamps, which use an epoch of 1970-01-01T00:00:00.000Z. In other words, Midnight Jan 1st 1970 UTC is the 0 timestamp. Sometimes, such timestamps are referred to as "epoch time". That's a misnomer in my opinion, but even still - they are always UTC based. There is no time zone, and thus they are the same for the whole world.

format datetime specific timezone

Stolen from here

This solution works by using the getTimeOffset() (which returns the time difference between UTC time and local time, in minutes) function to find the UTC time offset of a given location and changing it to milliseconds, then performing calculations from UTC to return a time for a different time zone.

/** 
 * function to calculate local time
 * in a different city
 * given the city's UTC offset
 */
function calcTime(city, offset) {

// create Date object for current location
var d = new Date();

// convert to msec
// add local time zone offset
// get UTC time in msec
var utc = d.getTime() + (d.getTimezoneOffset() * 60000);

// create new Date object for different city
// using supplied offset
var nd = new Date(utc + (3600000*offset));

// return time as a string
return "The local time in " + city + " is " + nd.toLocaleString();
}

This solution will work, but it's simpler to express timezone in minutes and adjust the UTC minutes.

Please let me know if this works for you!

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