Javascript for Designer/Beginer

Can anyone suggest good book or video for learning Javascript? I have been using Spry and iBox/thickbox/lightbox in recent projects and finding that if I want to add more effects then I will need to start learning Javascript. I would like to learn enough to help me use and understand frameworks such as Spry.

I am a designer that mainly uses CSS/XHTML and I know a bit of actionscript so any tutorials that are at a level of going straight into JS coding by example would be perfect.

Cheers