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JavaScript

/* 
* Author: Mohammad M. AlBanna
* Website: MBanna.me
* Description: Get the current time in different time zone 
*/

//Check daylight saving time prototype
Date.prototype.stdTimezoneOffset = function() {
    var jan = new Date(this.getFullYear(), 0, 1);
    var jul = new Date(this.getFullYear(), 6, 1);
    return Math.max(jan.getTimezoneOffset(), jul.getTimezoneOffset());
}

Date.prototype.dst = function() {
    return this.getTimezoneOffset() < this.stdTimezoneOffset();
}

var today = new Date();
var isDST = today.dst() ? true : false;
var pstOffset = isDST ? 7 : 8;
var cstOffset = isDST ? 5 : 6;
var estOffset = isDST ? 4 : 5;
var gmtOffset = 1;

pstOffset = pstOffset * 60 * 60 * 1000;
cstOffset = cstOffset * 60 * 60 * 1000;
estOffset = estOffset * 60 * 60 * 1000;
gmtOffset = gmtOffset * 60 * 60 * 1000;

var todayMillis = today.getTime();
var timeZoneOffset = (today.getTimezoneOffset() * 60 * 1000);

var curretPST = todayMillis - pstOffset; 
var curretCST = todayMillis - cstOffset; 
var curretEST = todayMillis - estOffset;
var curretGMT = todayMillis - gmtOffset;

addP("PST Time : " + new Date(curretPST).toUTCString());
addP("CST Time : " + new Date(curretCST).toUTCString());
addP("EST Time : " + new Date(curretEST).toUTCString());
addP("GMT Time : " + new Date(curretGMT).toUTCString());
addP("Local Time : " + new Date(today.getTime() - timeZoneOffset ).toUTCString());

function addP(value){
    var p = document.createElement("p");
    p.innerHTML = value;
    document.body.appendChild(p);
}