[HankMcCoy]

I have to admit, I have never seen

.) for-loops used this way

.) an OR-operator in a for loop

.) +a as a shortcut for a.toString()

.) syntax like g&&R(a) (line 24)

.) syntax like a[j^i==j] (line 29)

Where can I learn/read about advanced stuff like this, searching for this information on google is very hard, as I lack the correct terms ...

[tikhonj]

I think most of that syntax isn't so much "advanced" as simply not used in practice--it's too hard too read. Additionally, it uses basic operators which you should know (except maybe for "^" which is bitwise xor).

The best thing to do would be go through the basics of JavaScript and learn exactly how everything behaves. You should be able to answer questions like "is 24&&4 === true?" pretty easily.

If you have a bit of time on your hands, reading the standard will teach you all you need to know.

Of course, from a purely professional stand point, this is probably not the best use of your time (although knowing the language inside-out is important); using code like this in production code is a bad idea--it makes maintenance much more difficult.