this book teach the JavaScript a programming language that allows you to implement complex things on web pages. Every time a web page does more than just sit there and display static information for you to look at — displaying timely content updates, or interactive maps, or animated 2D/3D graphics, or scrolling video in website
Most programming languages contain good and bad parts, but JavaScript has more than its share of the bad, having been developed and released in a hurry before it could be refined. This authoritative book scrapes away these bad features to reveal a subset of JavaScript that's more reliable, readable, and maintainable than the language as a whole—a subset you can use to create truly extensible and efficient code.
By the end of this book you will have gained a sound understanding of JavaScript and be able to add exciting dynamic scripts to your own web pages.