import os source = '../src/Stats.js' output = '../build/stats.min.js' os.system('java -jar compiler/compiler.jar --language_in=ECMASCRIPT5 --js ' + source + ' --js_output_file ' + output) with open(output,'r') as f: text = f.read() with open(output,'w') as f: f.write("// stats.js - http://github.com/mrdoob/stats.js\n" + text)