Developer's Information

This page is targeted at developers wishing to delve deeper into Proj4js internals.

Git access

The git repository for Proj4js can be found at

Due to difficulties encountered extracting the code from the MapBuilder project, we were unable to preserve the SVN history. However, the history will continue to be available through the MapBuilder? SVN. The relevant directories are:

Building Proj4js

1.3.1 and later



The proj4js/build directory contains some scripts that can be use to build a single file ( and compressed ( versions of the Proj4js library. The build process is controlled by the file library.cfg. To build the library:

cd proj4js/build

By default, all projection class code is included in the resulting file. If only a subset of projections are required, then the library.cfg file can be edited to include or exclude the pieces required. For example, if your application will only ever use EPSG:27563 and the LCC projection, library.cfg can be edited to be:





Similarly, OLprototype.cfg is the build configuration file used to create the OLprototype.js file with the OpenLayers? build script. In general, there will be no need to modify this file.

The test suite

Adding projection class code

Datum Transforms

Last modified 4 years ago Last modified on Sep 16, 2013 11:55:40 AM