Convert date to another timezone in JavaScript

For moment.js users, you can now use moment-timezone. Using it, your function would look something like this:

function toTimeZone(time, zone) {
    var format = 'YYYY/MM/DD HH:mm:ss ZZ';
    return moment(time, format).tz(zone).format(format);
}

Okay, found it!

I'm using timezone-js. this is the code:

var dt = new timezoneJS.Date("2012/04/10 10:10:30 +0000", 'Europe/London');
dt.setTimezone("Asia/Jakarta");
console.debug(dt); //return formatted date-time in asia/jakarta

Stolen shamelessly from: http://www.techrepublic.com/article/convert-the-local-time-to-another-time-zone-with-this-javascript/6016329

/** 
 * 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 function is useful to calculate time zone value by providing name of a city/country and offset value

Most desktop (not mobile) browsers except Safari support the toLocaleString function with arguments, older browsers usually ignore the arguments.

new Date().toLocaleString('en-US', { timeZone: 'Asia/Jakarta' })

Got it !

Wanted to force the date shown = server date, no mattter the local settings (UTC).

My server is GMT-6 --> new Date().getTimezoneOffset() = 360.

myTZO = 360;
myNewDate=new Date(myOldDateObj.getTime() + (60000*(myOldDateObj.getTimezoneOffset()-myTZO)));
alert(myNewDate);

Set a variable with year, month, and day separated with '-' symbols, plus a 'T' and the time in HH:mm:ss pattern, followed by +01:00 at the end of the string (in my case the time zone is +1). Then use this string as the argument for the date constructor.

//desired format: 2001-02-04T08:16:32+01:00
dateAndTime = year+"-"+month+"-"+day+"T"+hour+":"+minutes+":00+01:00";
var date = new Date(dateAndTime );

I should note that I am restricted with respect to which external libraries that I can use. moment.js and timezone-js were NOT an option for me.

The js date object that I have is in UTC. I needed to get the date AND time from this date in a specific timezone('America/Chicago' in my case).

 var currentUtcTime = new Date(); // This is in UTC
 // Converts the UTC time to a locale specific format, including adjusting for timezone.
 var currentDateTimeCentralTimeZone = new Date(currentUtcTime.toLocaleString('en-US', { timeZone: 'America/Chicago' }));
 console.log('currentUtcTime: ' + currentUtcTime.toLocaleDateString());
 console.log('currentUtcTime Hour: ' + currentUtcTime.getHours());
 console.log('currentUtcTime Minute: ' + currentUtcTime.getMinutes());
 console.log('currentDateTimeCentralTimeZone: ' +        currentDateTimeCentralTimeZone.toLocaleDateString());
 console.log('currentDateTimeCentralTimeZone Hour: ' + currentDateTimeCentralTimeZone.getHours());
 console.log('currentDateTimeCentralTimeZone Minute: ' + currentDateTimeCentralTimeZone.getMinutes());

UTC is currently 6 hours ahead of 'America/Chicago'. Output is:

currentUtcTime: 11/25/2016
currentUtcTime Hour: 16
currentUtcTime Minute: 15
currentDateTimeCentralTimeZone: 11/25/2016
currentDateTimeCentralTimeZone Hour: 10
currentDateTimeCentralTimeZone Minute: 15

If you just need to convert timezones I have uploaded a stripped-down version of moment-timezone with just the bare minimum functionallity. Its ~1KB + data:

S.loadData({
    "zones": [
        "Europe/Paris|CET CEST|-10 -20|01010101010101010101010|1GNB0 1qM0 11A0 1o00 11A0 1o00 11A0 1o00 11A0 1qM0 WM0 1qM0 WM0 1qM0 11A0 1o00 11A0 1o00 11A0 1qM0 WM0 1qM0|11e6",
        "Australia/Sydney|AEDT AEST|-b0 -a0|01010101010101010101010|1GQg0 1fA0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1fA0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0 1cM0|40e5",
    ],
    "links": [
        "Europe/Paris|Europe/Madrid",
    ]
});
let d = new Date();
console.log(S.tz(d, "Europe/Madrid").toLocaleString());
console.log(S.tz(d, "Australia/Sydney").toLocaleString());

there is an npm module called 'timezones.json' you can use for this; it basically consists of a json file with objects containing information on daylight savings and offset,....

for asia/jakarta it would be able to return this object:

{
  "value": "SE Asia Standard Time",
  "abbr": "SAST",
  "offset": 7,
  "isdst": false,
  "text": "(UTC+07:00) Bangkok, Hanoi, Jakarta",
  "utc": [
    "Antarctica/Davis",
    "Asia/Bangkok",
    "Asia/Hovd",
    "Asia/Jakarta",
    "Asia/Phnom_Penh",
    "Asia/Pontianak",
    "Asia/Saigon",
    "Asia/Vientiane",
    "Etc/GMT-7",
    "Indian/Christmas"
  ]
}

you can find it here:

https://github.com/dmfilipenko/timezones.json

https://www.npmjs.com/package/timezones.json

hope it's useful

You can try this also for convert date timezone to India:

var indianTimeZoneVal = new Date().toLocaleString('en-US', {timeZone: 'Asia/Kolkata'});
var indainDateObj = new Date(indianTimeZoneVal);
indainDateObj.setHours(indainDateObj.getHours() + 5);
indainDateObj.setMinutes(indainDateObj.getMinutes() + 30);
console.log(indainDateObj);

I don't know an easy method to convert a date object to any time zone, but if you want to convert it to the local time zone, you can just convert it with Date.prototype.getTime() to the corresponding number of milliseconds, and back again.

date = new Date('2016-05-24T13:07:20');
date = new Date(date.getTime());

For example, date.getHours() will now return 15 instead of 13 if you are, like me, in Austria (and it's summer).

I've read that the various datetime functions may exhibit non-standard behaviour in some browsers, so test this first. I can confirm that it works in Chrome.