If you like Sublime Text, there are very few text editors which rival it. In the same vein, there is Atom (which I think is really good, a bit slow, but the trade off is that when you know HTML, JavaScript and CSS you can hack it and make plugins for it) -- it's also free and Open Source.

I work on WebKit.

On the JavaScript side, browsers are definitely compilers. They are actually very interesting compilers.

In the WebKit engine, JavaScript is first compiled to bytecode, then it is first interpreted. If some part of the code becomes "hot" (runa a lot), it tiers up to a first level of compilation-to-native (JIT compilation). In the case of WebKit, the first tier is the baseline JIT, it does little more than the interpreter but improves various types of operations. Then if the code remains hot, it will tier up more, to optimizing compilers: first DFG, then FTL.

The other popular engines, Ion (Gecko) and V8 (blink), use similar techniques.

On the HTML/CSS side, I would not call a web engine a compiler or interpreter, it is just a runtime: some custom code that is called. Many parts could be written as interpreters but are not for simplicity on the implementation side. WebKit is a little different in that it compiles some things at that level, other engines don't do that.

I doubt you will learn much about compilers from Udacity. What is on Udacity tends to be overly basic.

There are real compilers courses online:

• https://www.coursera.org/course/compilers

• https://www.coursera.org/course/automata (Not directly compilers but a very useful tool to build compiler or to optimize some languages).

If you know C++, you can also learn from real projects:

• http://llvm.org - Well documented compiler, modern code base, fantastic community.

• http://www.webkit.org - A complete web engine, I can help you navigate the compiler if you are interested.