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javascriptdatedatetimetimetimezone
Zia Ur Rehman
Zia Ur Rehman

Reputation: 23

How to convert date time saved in New York timezone to local time zone in javascript?

I am getting date time stored as string in New York timezone (GMT -4) format from third-party website. I want to convert it to local time zone using javascript. Date time is saved in following format

"2019-04-15 19:09:16"

I know i can achieve this through MomentJS but I want to know if there is any simple solution beside loading all library to convert date time to local timezone.

On Chrome expected output could be achieved by appending GMT-4 at the end of date and

new Date("2019-04-15 19:09:16 GMT-4")

But this solution doesn't work on Firefox because of invalid format.

Upvotes: 1

Views: 6894

Answers (1)

Matt Johnson-Pint
Matt Johnson-Pint

Reputation: 241420

If you actually know that the offset is UTC-4, then you simply need to reformat your string to be compliant with the ECMAScript Date Time String Format, which is a simplification of the ISO 8601 Extended Format.

new Date("2019-04-15T19:09:16-04:00")

However, note that New York is on US Eastern Time, which is actually in daylight saving time for the date and time you provided. In other words, it isn't UTC-4 (EST), but rather UTC-5 (EDT). So for that example, it should be:

new Date("2019-04-15T19:09:16-05:00")

But what if you don't know which offset it is for a given time zone on a particular date and time? After all, time zones, daylight saving time transitions, and associated offset are different all over the world, and have changed throughout history. So one cannot just assume a time zone has a single number that is its offset. (Read more under "Time Zone != Offset" in the timezone tag wiki.)

Presently, JavaScript cannot help you with that on its own. Instead, you'll need to use a library, such as the ones referenced here.

For example, using Luxon, you can do the following:

luxon.DateTime.fromISO("2019-04-15T19:09:16", { zone: "America/New_York" }).toJSDate()

In the future, we hope to solve this in the JavaScript language via Temporal objects - which are still in the ECMAScript proposal stage.

Upvotes: 2

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