I found the book "DOM Scripting" great. There's a brief intro to javascript syntax, then alot of focus on using javascript with the DOM and making sure you do i

I found the book "DOM Scripting" great. There's a brief intro to javascript syntax, then alot of focus on using javascript with the DOM and making sure you do it according to some best practices. The book finishes with an intro to ajax and is followed by a book called "Bulletproof AJAX" by the same bloke. The gracefully degrading and unobtrusive use of javascript is important, and the author of these books preaches it well.