Question

How can I gather the visitor’s time zone information?

I need both:

1. the time zone (for example, Europe/London)
2. and the offset from UTC or GMT (for example, UTC+01)

Answer 1

Using getTimezoneOffset()

You can get the time zone offset in minutes like this:

var offset = new Date().getTimezoneOffset();
console.log(offset);
// if offset equals -60 then the time zone offset is UTC+01

The time-zone offset is the difference, in minutes, between UTC and local time. Note that this means that the offset is positive if the local timezone is behind UTC and negative if it is ahead. For example, if your time zone is UTC+10 (Australian Eastern Standard Time), -600 will be returned. Daylight savings time prevents this value from being a constant even for a given locale

• Mozilla Date Object reference

Note that not all timezones are offset by whole hours: for example, Newfoundland is UTC minus 3h 30m (leaving Daylight Saving Time out of the equation).

Please also note that this only gives you the time zone offset (eg: UTC+01), it does not give you the time zone (eg: Europe/London).