Computer books are written at different levels and for different purposes. When you are looking to buy a book on Javascript (or any other computer related topic) you need to consider what level of knowledge that you already have in the subject area and what your purpose is in wanting to purchase a book.
Level
Computer books can be written for beginners where no previous knowledge of the subject is assumed. They might be written at an intermediate level or advanced level where at least some and perhaps quite a lot of prior knowledge is assumed. Often computer books have a notation on the back of the book that helps identify which level that a book targets. "For Dummies", "Complete Idiot's Guide" and "In Easy Steps" books are aimed at the beginner.Purpose
With Javascript books, the books may be intended for one of several different purposes. When you are looking to purchase a Javascript book in order to learn Javascript programming there is no point in purchasing a book that just provides you with the way to code a small range of scripts or which contains a complete Javascript reference but no tutorials on how to use them. If you are just looking for how to code a particular script then you don't need a complete introduction to programming.Subject
You will probably find some information on Javascript on a book on HTML. Similarly a Javascript book will probably mention animation and DHTML. You will find a lot more information about Javascript in a book that deals specifically about Javascript and a lot more about creating animation effects using Javascript in a DHTML book than you will in a general Javascript one.
