JSFiddle - React, Tailwind, and code Playground

HTML

<div id="clockbox"></div>
<div id="clock"></div>

<div id="bombay"></div>

<div id="singapore"></div>

JavaScript

tday  =new Array("Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday");
tmonth=new Array("January","February","March","April","May","June","July","August","September","October","November","December");

function GetClock(){
d = new Date();
nday   = d.getDay();
nmonth = d.getMonth();
ndate  = d.getDate();
nyear = d.getYear();
if(nyear<1000) nyear=nyear+1900;


document.getElementById('clockbox').innerHTML=""+tday[nday]+", "+tmonth[nmonth]+" "+ndate+", "+nyear+"";
document.getElementById('clock').innerHTML=""+tday[nday]+", "+tmonth[nmonth]+" "+ndate+", "+nyear+"";
setTimeout("GetClock()", 1000);
}
window.onload=GetClock;
function calcTime(city, offset) {

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

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

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

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

}
document.getElementById('bombay').innerHTML=calcTime('Bombay', '+5.5');
document.getElementById('singapore').innerHTML=calcTime('Singapore', '+8');