How can I convert date string to data in javascript in different timezone?

Question

I need to convert a Date string to date object in javascript. What I receive is something like:

utc='2021-02-03T02:44:51.118Z'.  # time in utc

local='2021-02-03T12:44:51.118Z' # time in local timezone

for above two strings, each of which represent a different timezone. How can I create a Date object from them to represent the right timezone? Ideally I'd like to convert them to epoch format but don't know how to calculate offset correctly.

I have looked at getTimezoneOffset method but it doesn't consider daylight saving time.

Answer 1

You can use Date object and method toLocaleString() .

When you use the string '2021-02-03T02:44:51.118Z' or '2021-02-03T12:44:51.118Z' , they are all UTC time.

When you use the string '2021-02-03T12:44:51.118+10:00' , it is time zone +10:00 (Dumont d'Urville Station).

To convert UTC to local time zone, use this code:

let time = "2021-02-03T02:44:51.118Z"

let t = new Date(time)
console.log(t.toLocaleString("en-US", {timeZone: "Antarctica/DumontDUrville"}));

To convert local time to UTC, use this code:

let local = "2021-02-03T12:44:51.118+10:00"
let t = new Date(local)
console.log(t.toLocaleString("en-US", {timeZone: "UTC"}));

Note:

• Z means "zero hour offset" also known as "Zulu time" (UTC)
• Can see list of local timeZone code at here