Is there a free/open-source JavaScript-to-JavaScript compacting compiler (like Google's)?

Question

If you look at the source of Google pages with JavaScript, you'll find that the JavaScript is clearly not readable -- or maintainable. For example, all variables and functions are one-letter named (at least, the first 26 are...); there are no extraneous white-spaces or linebreaks; there are no comments; and so on.

The benefits of this compiler are clear: pages load faster, JavaScript execution is faster, and as a bonus, competitors will have a hard time understanding your obfuscated code.

Clearly, Google is using some sort of a JavaScript-to-JavaScript compacting compiler. I am wondering if what they're using is an in-house tool? If not, what are they using? Are there any publicly available (ideally, free/open-source) tools of that sort?

Answer 1

You may be looking for GWT - it's Java-to-JavaScript rather than JavaScript-to-JavaScript, but you may still find it useful.

I can't comment on what internal tool, if any, we use for JavaScript-to-JavaScript. (To be honest, I don't even know offhand... I'd have to look it up before explicitly not telling anyone :)

Answer 2

YUI Compressor is a Java app that will compact and obfuscate your Javascript code. It is a Java app that you run from the command line (and would probably be part of a build process).

Another one is PHP Minify, which does a similar thing.

Answer 3

It's actually pretty unlikely to be JS->JS, much more so to be Java->JS. These days I believe the recommended JS compressor (for this is what they're called) is the YUI compressor, but others like /packer/ exist

Answer 4

Another one is ShrinkSafe that is part of Dojo but may be used stand-alone (either in a build script, command line or at the website): http://shrinksafe.dojotoolkit.org/

Answer 5

Crockford.com's JSMin is one step in that direction, assuming you're only looking for minimization and not obfuscation.