JavaScript: how to get date time at a specified timezone-CodePudding

Is there a way to get a time that is local to a specified timezone in JavaScript? Basically, I'm looking for a way to say, what is the ISO time string of 2pm in New York?

I have a hack to do so, where the date is a parse-able date string, and tz is a timezone identifier, such as America/New_York.

function getDateInTZ(date, tz) {
  const formatter = new Intl.DateTimeFormat([], {
    year: "numeric",
    month: "numeric",
    day: "numeric",
    hour: "numeric",
    minute: "numeric",
    second: "numeric",
    fractionalSecondDigits: 3,
    timeZone: tz,
  });
  const localDate = new Date(date);
  const localDateAtTZ = new Date(formatter.format(localDate));
  const tzOffset = localDate.getTime() - localDateAtTZ.getTime();
  return new Date(localDate.getTime()   tzOffset);
}

and it has the following behavior

getDateInTz("2021-07-01 20:05", "America/Chicago").toISOString(); // 2021-07-02T01:05:00.000Z
getDateInTz(new Date("2021-12-05 20:05"), "America/Chicago").toISOString(); // 2021-12-06T02:05:00.000Z

getDateInTz("2021-12-06T02:05:00.000Z", "America/New_York").toISOString(); // 2021-12-06T02:05:00.000Z if local time is NY
getDateInTz("2021-12-06T02:05:00.000Z", "America/New_York").toISOString(); // 2021-12-06T07:05:00.000Z if local time is UTC

While the above solution works in Chrome, it doesn't work on Firefox because FF is unable to do Date.parse on the output of formatter.format(). Which leads me to think that it's not a correct solution.

Has anyone run into this requirement before, and have a good solution for it?

CodePudding user response：

You can use something like this:

const actualDate = new Date()
actualDate.toLocaleString('en-US', { timeZone: 'America/New_York' })

CodePudding user response：

Does this solve your question?

function getDateInTZ(date, tz) {
  return new Date(date).toLocaleString('en-US', { timeZone: tz })
}

console.log(getDateInTZ("2021-07-01 20:05", "Asia/Kolkata"))
console.log(getDateInTZ("2021-07-01 20:05", "America/Chicago"))
console.log(getDateInTZ("2021-12-06T02:05:00.000Z", "America/New_York"))