Industrial Strength Application Development in JavaScript

Inspired by the work of Douglas Crockford, I have been developing a JavaScript application using full blown development techniques. JavaScript is definitely a misunderstood and underestimated programming language, and I have found it to be a pretty good hybrid of object-oriented and functional techniques. I have even done some cool things with it that would not be possible in a statically typed language. I have found that with proper unit testing and debugging tools, its dynamic typing has caused me few problems.

So what tools can I recommend for industrial development in JavaScript? Everything below is an absolute must for my needs:

jQuery

• What it does: Ajax, DOM-modification, and general utility functions
• As Jeff Atwood pointed out, there is no good reason to write low-level JavaScript to manipulate the DOM with today, now that there are tons of high quality JavaScript libraries to help out.
  

QUnit

• What it does: Simple unit testing, compatible with jQuery
  
• I tried out a few other unit testing frameworks, but QUnit is the simplest one by far and just gets the job done.
  

JavaScript Lint

• What it does: Identifies most textual errors in JavaScript files.
• Indispensable tool to find that missing semicolon that is causing that weird error.
• Note for TextMate users: Use the JavaScript Tools bundle instead of downloading it from the official site.
  

Firebug

• What it does: Firefox plugin. In addition to excellent DOM manipulation, it makes a great JavaScript debugger.
  

In Addition, Mozilla's JavaScript Reference is a must for any serious JavaScript developer.

Well, I hope this gets you started. If you have any other suggestions, let me know!