tz-lookup

tz-lookup

This is a little module that allows you to look up the current time zone of a location, given it's latitude and longitude. I wrote it because the existing Node module that does this (tzwhere) was far too slow to be useful in a production setting. This module attempts to ameliorate that.

Usage

To install:

npm install tz-lookup

To use:

> var tzLookup = require("tz-lookup");
> tzLookup(42.7235, -73.6931, function(err, tz) {
>   console.log(tz);
> });
"America/New_York"

There are two data files: a small index file (which is loaded on the first call to tzLookup()) and larger polygon files on disk that are loaded as needed, and then discarded. Performance of any given query will vary depending on its location on the globe, but should be generally high in any case.

Previous versions of this module stored the entire timezone database in RAM. This was inefficient for many use-cases and is no longer done. RAM usage from this module should generally be low.

Regenerating the Database

If you wish to regenerate the database, replace data/tz_world.json with a new version, and run bin/convert. This will update the backing data that this module uses.

tz_world.json should, itself, be a GeoJSON of the global data found on this website: http://efele.net/maps/tz/ It was last updated by us in December 2012.