How do JavaScript interpreters/engines work?

Question

Hi,

I'm interested to find out how the JavaScript interpreter (engine if you like) works. I'm aware that JavaScript isn't compiled.I have looked at the ECMA specification, but it doesn't explain how the actual engine works.

The main reason why I'm asking this is because I'd like to understand why IE7 behaves slightly differently to IE8 or Firefox 3.5+.

I suspect that certain function calls get handled in a different order, but I'd like to know for sure.

I have also watched few videos by google talks on JavaScript optimization along with the JavaScript: Good Parts video. These touched on the topic briefly.

Thank you

Answer 1

If you can deal with low-level languages, look at the sources of V8 or TraceMonkey and research them. It is a bit difficult way to understand the internals of the JavaScript engines, but it is quite interesting.