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I know that new Date().getTimezoneOffset() accounts for the local user's timezone & DST, but how to calculate the current local time in say Timbuktu for an arbitrary time in the future?

Jonathan Leffler
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Mark
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3 Answers3

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JavaScript does not have a timezone database built in to the language (as can be seen by perusing the spec). Instead it only has the concept of "local time" and "UTC time," with there being only one local timezone.

It is possible there is a browser API for getting a timezone database, but I have never heard of it. There are some third-party projects that interface with such databases; a quick search turns up timezone-js.

Domenic
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I doubt there is any algorithm that could give you what you want. The nations of the world often choose not to follow the standard time zone rules. Worse the changeover dates for DST are different.

There are 3 sources that I can think of to check:

Jeppesen, a subsidiary of Boeing, is the primarily civilian supplier for the entire world for aeronautical navigation information. I just checked my old Jeppesen manual that I ceased getting weekly updates for when I retired 13 years ago. It gives the time zone for all major airports in the world and the dates of their DST change. Go here for contact info. I would suspect that by now it's conveniently available electronically, but Jeppesen doesn't give anything away for free.

ICAO, the International Civil Aviation Organization (part of the UN now I think) would I think maintain that information, but I'm not so sure about the DST data. Their data, I believe, is available either free or for a nominal charge.

IATA, the International Air Transport Association, might also maintain that data.

I would think that the last two organizations might respond favorably to a simple request for a URL with that data if they know of one.

Also, if can get ahold of any airline dispatcher working international flights, they would have to have that information available.

Also, check this and others you'll see if you Google "airline time zone and dst data."

onkar
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Terry
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The easy part is accounting for timezones. You can find the default (+0) timezone by just subtracting timezone*60*60 seconds from the date, then adding the new timezone*60*60 to the date.

Then it's just a matter of making the time you want, using:

d = new Date(year, month, day, hours, minutes, seconds, milliseconds)
DanRedux
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