Felix Geisendorfer has posted part one of a series aiming to help PHP developers get into one of the web's other most popular languages - Javascript.
It's actually the beginning of a little series (2 or 3 parts) that is going to be targeted at php developers who've only used JS by merging snippets/libraries together without really learning the language itself.
He starts with the basics - his environment, variables, arrays, etc. He gets into a bit higher level with objects in Javascript and functions as well as including the creation of classes.