> Ever try to use different JavaScript tools with conflicting jQuery versions? Yeah, that sucks.
That's what is great about YUI, where you have most tools you need to build whatever you like (50+ components), and they're all tested and guaranteed to work together every release. http://yuilibrary.com/yui/docs/guides/
> How about trying to figure out how to make 20 javascript include files load quicker as one request? Yeah that sucks too.
No it doesn't. YUI's modular system is completely centered around the concept of CDN combo-loading. It's dead-simple.
> Performance? Let me just point to the old Facebook mobile app made with JS & HTML5. It sucked. Enough said.
"HTML5" isn't a magic bullet that automatically makes everything awesome. You still have to design apps correctly. The author didn't elaborate on any specifics of why it "sucked", so I don't have much to go on to counter. JS would seem to perform quite well for anything FB needs to do in a Web app (display text, pictures, links), so any issues were likely just bad design.
> How about unit testing JavaScript? I've never tried it, but it sure sounds like fun.
It's actually pretty simple (and dare I say fun?). I've written hundreds of test cases. There are plenty of JS testing frameworks out there, including Y.Test (written by Nicholas Zakas, http://yuilibrary.com/yui/docs/test/) which can be used for YUI and non-YUI applications.
YUI itself has 6,300+ unit tests covering everything from core modules to website examples, and every single one of them pass 24/7 (or is fixed immediately).
> My biggest problem with JavaScript is code security. If I make some awesome product, there is no way to protect my code. How can we expect game makers to write apps in 100% JavaScript and HTML5 if they can't protect their intellectual property?
Is this arguing security, or IP protection? There's a reason why every proprietary plugin/runtime for the Web ultimately falls to the open competitor. A 50-line JS widget can easily be "stolen", but how much was it worth to begin with? View-source (IMO) is one of the best features of the Web, because it enables the Web to progress and evolve at a pace otherwise impossible. "Awesome products" have been made by Google, Facebook, Yahoo, Twitter, countless startups, and I don't think source-code visibility has harmed them in any significant way.
In conclusion, if I read this post 10 years ago, the author would have a solid case. But tens of thousands of developers have helped create an incredibly supportive ecosystem that provide just about every tool you need, just open your mind a little bit. JavaScript absolutely does not suck.