Ok, I can understand both Seanneo and Andrews way of thinking. However, if it were me. I'd go with what Seanneo said if you ever plan on expanding your knowledge into other (more advanced) programming languages. While learning PHP's syntax may be the easiest, it will get you into some bad habits and you won't learn much about data types. However, if it's simply the syntax your stuck on, it may or may not help anyway.

If you want to learn JavaScript, you're best bet is to think of some small projects and break it down into steps; then Google.

Lets say you want to build a calculator where you type in "x+x" and JavaScript solves it.
You would need first need to get the text input's value.
Separate the two numbers.
Make sure the two numbers are integers and is not a string.
Add the two numbers.
Display the results.

xHTML/CSS (as said) is more of a markup while JavaScript is also Client Side, it's more of a programming language. PHP, on the other hand, is a server side programming language.

Hope this helps,
- Phaaze