[hakann]

Watch Douglas Crockford's video series that he made at Yahoo. Get a copy of his book and read it.

Make sure you understand the prototypical nature of Javascript as opposed to the class structure in other languages and how to use it effectively. Also make sure to understand scope, how "this" keyword relates to scope and finally callback functions.

That is pretty much it. JS is very powerful once you get comfortable with it. It was designed in a very short time (~2 weeks) so it has some quirks but do not let those get to you.