JAVASCRIPT

javascript set date to timezone

var d = new Date("2020-04-13T00:00:00.000+08:00"); /* midnight in China on April 13th */
d.toLocaleString('en-US', { timeZone: 'America/New_York' });
//=> "4/12/2020, 12:00:00 PM"
// (midnight in China on April 13th is noon in New York on April 12th)

get timezone javascript

const timezone = Intl.DateTimeFormat().resolvedOptions().timeZone;
console.log(timezone);

js get current timezone offset

console.log(new Date().getTimezoneOffset()/-60) // offset in hours

get offset from timezone javascript

// Following function can be used to return the UTC offset given a timezone:

const getTimezoneOffset = (timeZone, date = new Date()) => {
  const tz = date.toLocaleString("en", {timeZone, timeStyle: "long"}).split(" ").slice(-1)[0];
  const dateString = date.toString();
  const offset = Date.parse(`${dateString} UTC`) - Date.parse(`${dateString} ${tz}`);
  
  // return UTC offset in millis
  return offset;
}


//It can be used like:

const offset = getTimezoneOffset("Europe/London");
console.log(offset);
// expected output => 3600000

timezone offset to timezone in javascript

getGMT() {
    let gmtFigure = new Date().getTimezoneOffset() / -60;
    let gmtSign = gmtFigure >= 0 ? '+' : '-';
    let gmtlength = this.digits_count(gmtFigure);
    let gmt = 'GMT';
    if (gmtlength == 1) {
      gmt += gmtSign + '0' + Math.abs(gmtFigure);
    } else if (gmtlength > 1) {
      gmt += gmtSign + Math.abs(gmtFigure);
    }
    return gmt;
  }


digits_count(n) {
    var count = 0;
    n = Math.abs(n);
    if (n >= 1) ++count;
    while (n / 10 >= 1) {
      n /= 10;
      ++count;
    }
    return count;
  }

javascript date timezone

// this example takes 2 seconds to run
const start = Date.now();

console.log('starting timer...');
// expected output: starting timer...

setTimeout(() => {
  const millis = Date.now() - start;

  console.log(`seconds elapsed = ${Math.floor(millis/1000)}`);
  // expected output : seconds elapsed = 2
}, 2000);