Automatically detect user's current local time with JavaScript or PHP

Question

I often need to display information based on or influenced by a user\'s actual local time which differs across time zones. Is there a reliable way of getting a user

Answer 1

In short no.

I would suggest using server side time, and have the ability for the user to choose their time zone.

You could possibly calculate default time zones for users based on heuristics around their IP address, but this is open to error.

You should be able to extract client side time zone information through javascript / Ajax, but as with the time itself this is also open to error.

My recommendation: Let users choose their time zone with a sensible default based on where you expect your users to be.