As you know, JavaScript has all Java keywords reserved. Does anyone know why? JavaScript discourages using these Java keywords, but they appear to work fine when used as identifiers.
The story is that when they were developing JavaScript (originally called Oak I believe (apparently, I got the languages mixed up the previous statement about it's original name is incorrect.)), Netscape partnered with Sun to develop it. To entice the Java community, they wanted to make JavaScript like Java, so that Java developers would feel more comfortable with it, and that is the reason why they are so similar.
What you have to remember about designing a language is that you really only get one shot at defining keywords, without having a new version of the language break existing code. It's much easier to reserve a word at the beginning and not use it than try and reserve it later. This is especially true for things like JavaScript where the person developing the script has no control over which browser it's going to run in (this happens now i know, but it could be a lot worse). Could you imagine how madding it would be to find out that the next version of JavaScript which is adopted by the new browser suddenly won't run your application, because they reserved a new keyword?