Prepro.js
A JavaScript based preprocesssor language for JavaScript
Copyright (c) 2011 - 2016 Juerg Lehni http://scratchdisk.com/
Prepro.js is a simple preprocesssor for JavaScript that speaks JavaScript, written in JavaScript, allowing preprocessing to either happen at build time or compile time. It is very useful for libraries that are built for distribution, but can be also compiled from separate sources directly for development, supporting build time switches.
Distributed under the MIT license.