How to create a snapshot of .js file -> webkit nwjs v8

Can somebody please explain me how to make a snapshot of javascript file in nodewebkit (now known as http://nwjs.io/) aplication.

I found this wiki http://ift.tt/1DJ6rNp but i cannot find nwsnapshot aplication.

Or where i need to input code (nwsnapshot --extra_code mytest.js mytest.bin) to convert - compile it?