Easy to minify with Google Closure in a Makefile, all you need is curl:

  build/project_min.js: build/project.js
    rm -f $@
    curl -s --data-urlencode 'js_code@build/project.js' --data-urlencode 'output_format=text' --data-urlencode 'output_info=compiled_code' http://closure-compiler.appspot.com/compile >> $@

h/t @enaeseth, edited for formatting