A few lines of Javascript can tell you which timezone the user's machine is set to. That is simply not true. You can get the localized timezone as provided by

A few lines of Javascript can tell you which timezone the user's machine is set to. That is simply not true. You can get the localized timezone as provided by the user's operating system. You would need a server side mapping of every time zone in language for both Olson and Windows. Even then, there are ambiguous timezone names, etc. The best you can do reasonably is calculate GMT offset, presence of daylight savings time, and if DST is present, then which hemisphere the user is in. From there, you can guess at a city/region with the largest population. See here: https://bitbucket.org/pellepim/jstimezonedetect/overview https://bitbucket.org/pellepim/jstimezonedetect/overview