Proj4node
Synchronous Proj4js slimmed down for Node.js
Usage
Convert a WGS884 coordinate to SWEREF99 TM.
var proj4node = sweref = p = sweref; console;
Syncing with Proj4js SVN repository
$ git clone https://github.com/icetan/proj4node.git
$ cd proj4node
$ ./connect-proj4js-repo.sh
Then read instructions from output.
Attributions
Important to note, I have only removed functionality from the original Proj4js project. All the hard stuff (algorithms and parsing) is solely thanks to the authors of Proj4js.