There are lots of online resources on javascript, and I mean LOTS. But it may take you awhile to go through it all to find what you specifically want. So there are LOTS of books you can get as well on javascript, but if you already have a basic understanding of javascript, most are way more than you need. When your working on something, you just need a quick and easy way to find a reference on an object or property or technique in javascript and this book will be exactly what you need.
This book was developed by the Microsoft PAG (Patterns and Practices) Team and ArtinSoft. It contains the most comprehensive and up to date ...