There are few options to gzip js/css file from command line in Windows.
Python standard library has gzip module that can gzip from command line:
Python standard library has gzip module that can gzip from command line:
It works pretty well and provides good compression rate. I compared size of the resulting file with result of Linux's gzip command with '-9' switch (best compression) and Python module produced smaller file (YMMV)
This python module will produce file with same name and extension 'gz':