If you are going to build any non trivial web applications with javascript, you will need to test your code. There are a lot of JavaScript unit testing libraries available and Dmitry Sheiko's book "Instant Testing with QUnit" is a practical book which shows you how to deploy QUnit and its plugins, to increase your efficiency when testing JavaScript code.
QUnit, developed by the jQuery team, is a powerful easy-to-use and flexible JavaScript unit testing framework which can be used to test any generic JavaScript code in the web browser. In the introductory chapters, the book begins by showing you how to set up the QUnit testing environment and getting acquainted with the QUnit framework.
It then introduces you the QUnit core assertion methods in addition to some assertion methods provided by QUnit plugins. The chapters in the book use real code samples to introduce you to QUnit testing. It's just a real shame that one of the first code examples the book uses, has a typo error in the javascript which makes you think twice whether or not you want to persevere with the code examples!
This book is definitely not a book for the novice, If you've never used QUnit before or are new to javascript testing you are advised to search the web for some basic introduction and tutorials on QUnit before you begin this book. For readers who use QUnit the book does have advanced sections on writing your own custom assertion plugins and running your QUnit tests from the command line.