It's very hard to reliably obfuscate JavaScript because the language is dynamic enough that you might refer to object fields or function names through dynamically-computed strings. Any attempt to obfuscate these runs up against the halting problem. So you have to rely on conservative approximations...

Packer (http://dean.edwards.name/packer/) will rename all local variables to single characters, along with removing all whitespace and optionally base-62 encoding the text. It also has a compression scheme, but it's trivial to defeat this by replacing eval() with document.write(). I think that's the best you can do with any JavaScript-only compressor.

I should probably mention that even JSMin'd text is a real pain to go through. Someone that's dedicated enough could do it (just like how people were reverse-engineering the Google Maps frontend), but nobody wants to read through a lot of code with no indentation.

Also, you're much better off with one large JSMin'd file than a bunch of streamed sections. Aside from being simpler, it's more to look through. Otherwise, people can sniff the stream through Fiddler or Analyzer and take a look at when segments are loaded, which often gives them more information than they'd have otherwise. And re-indenting 500k is a lot more of a pain than re-indenting a 500-byte segment.

if it is worth stealing, somebody will steal it. Its just the nature of client side scripts

If it is really that amazing just write about it on your blog and get famous

I disagree. If you're a clever programmer and can 'unobfuscate', you're likely to be clever enough to write it yourself anyway.

Obfuscation is there to prevent non-clever programmers from stealing parts/the whole source code, and it works.

If I were you I'd focus more on creating other nice stuff than trying to protect something inherently impossible to protect (client-side javascript).

Look at it this way: you can try hard to protect it even though you're likely to fail (as has been said, if it's worth stealing then it will be stolen), or you can avoid wasting your time to protect it and do something else valuable.

Would you rather have 1 great thing and have a possibility of preventing the 1st one from falling in wrong hands or have 2 great things? You can't always have everything. If your thing gets copied, you'll still have it. Also, I wouldn't worry much about a competitor that has to rely on copying you to keep up with you...

As a radical solution, you could publish the code and blog a lot about it, at least this way nobody can claim they wrote the code themselves...

PS: Sorry for all the "thing"s...

good advise. I will do that anyway. I'm sure people that copy don't realy know what they ar doing nyway

Measure the time-to-marketness of the feature. Instead of obfuscating JavaScript try spending your time to make the whole thing look as great as you can. Developing something like _Basecamp_ is easy but I doubt something as simple as Basecamp will be a success again--unless you improve it by an order of magnitude.

Don't bother obsfucating. A good programmer could make equivalent functionality without seeing a line of code. As an example, if you're familiar with a spreadsheet application then you can code the core functionality without reference to the original source. Is your script more complicated than a spreadsheet?

actually one part of it is a datasheet and another a form designer like in an IDE. I'm sure a good programmer would be able to re-create them. but they would probably resort to some Ajax kit. I try that and for lots of reasons wouldn't work or would be so heavy that it would become useless. So instead I spend over 3 months (which is a lot for JS) and wrote everything from from scratch. I guess my only hope is that the entire application becomes so good (which is mostly backend stuff) that even if someone has the JS they couldn't create the rest.

I know that everyone ("everyone") hates software patents.

Personally, I don't see what the difference is between patenting something made out of atoms that accomplishes a task in a new way, and patenting something made out of bits or memes that accomplishes a task in a new way.

If (a) you've come up with something new; (b) you're not morally opposed to software patents; (c) you have ~ $5k ; (d) you'll be able to detect infringers ; (e) the infringers will have deep pockets, then a software patent might be the right tool for the job. You can slap "patent pending" on long before the patent is issued, and collect licensing fees from legitimate companies that want to use your technology.

...all of which gets us back to the core point:

What is it that you hope to accomplish by obfuscating / patenting / whatever ?

A moral victory?

A competitive advantage for a few months?

Other?

Your answer to this question will dictate how you proceed.

The problem with patent is that large companies go out and copy what ever they want and then turn around and patent it. I wouldn't mind if some small potato took my code. Of course I wouldn't like it. but.. it would be really painful if a larger company did it. And they do. There is not much inovation with large companies. the good ones buy smaller compaines but some just take what they want. from open source or where ever they get their hands on.

So yes i would be for patent if it wasn't such a bad system where if you have moeny you could patent even things that don't belong to you.

That makes sense. I think you're better off using copyrights than patents. No application process, and typical friendlier court procedures.

With a patent, you need to prove in court that your idea was novel.

With copyrights, you just need to prove that you wrote your code first.

of course it can reverse engineered and of course it can be recreated but why at least not make it a bit harder for them by obsfucating the code. Good programmers wont bother copy your code anyway. Its those who will try to copy your code byte by byte you wont to discourage and obsfuctating is a good obstacle for these people.

The Javascript Compressor ( http://javascriptcompressor.com/ ) can compress and obfuscate Javascript code.

Thanks I'll look into that.

YUI Compressor works pretty well.