If you have ever been interested about the inner workings of JavaScript and haven’t already, you should take a look at several video lectures by Douglas Crockford. Douglas Crockford is a Senior JavaScript Architect at Yahoo! and has authored an O’Reilly Book: “JavaScript: The Good Parts“. The two I’d recommend starting off with are “The JavaScript Programming Language” that provides fundamental yet thorough information into the JS language such as objects and functions. Even if you have been using JS for an extended period of time, I’d recommend browsing through the lecture. The second video lecture is basically a continuation from the first, “Advanced JavaScript“.

These lectures do not delve into any of the current JS Libraries like YUI, mootools, or prototoype, but the lectures will help you extend those libraries as needed by project demands. The general Yahoo! UI (YUI) Library Theater page has many other video lectures available that get into utilizing the YUI JS library.