Book Image

Object-Oriented JavaScript - Second Edition

Book Image

Object-Oriented JavaScript - Second Edition

Overview of this book

JavaScript is the behavior, the third pillar in today's paradigm that looks at web pages as something that consists of clearly distinguishable parts: content (HTML), presentation (CSS) and behavior (JavaScript). Using JavaScript, you can create not only web pages but also desktop widgets, browser and application extensions, and other pieces of software. It's a pretty good deal: you learn one language and then code all kinds of different applications. While there's one chapter specifically dedicated to the web browser environment including DOM, Events and AJAX tutorials, the rest is applicable to the other environments Many web developers have tried coding or adopting some bits of JavaScript, but it is time to "man up" and learn the language properly because it is the language of the browser and is, virtually, everywhere. This book starts from zero, not assuming any prior JavaScript programming knowledge and takes you through all the in-depth and exciting futures hidden behind the facade. Once listed in the "nice to have" sections of job postings, these days the knowledge of JavaScript is a deciding factor when it comes to hiring web developers. After reading this book you'll be prepared to ace your JavaScript job interview and even impress with some bits that the interviewer maybe didn't know. You should read this book if you want to be able to take your JavaScript skills to a new level of sophistication.
Table of Contents (19 chapters)
Object-Oriented JavaScript Second Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Built-in Functions
Regular Expressions
Index

Inheriting the prototype only


As explained previously, for reasons of efficiency you should add the reusable properties and methods to the prototype. If you do so, then it's a good idea to inherit only the prototype, because all the reusable code is there. This means that inheriting the Shape.prototype object is better than inheriting the object created with new Shape(). After all, new Shape() only gives you own shape properties that are not meant to be reused (otherwise they would be in the prototype). You gain a little more efficiency by:

  • Not creating a new object for the sake of inheritance alone

  • Having less lookups during runtime (when it comes to searching for toString() for example)

Here's the updated code; the changes are highlighted:

function Shape() {}
// augment prototype
Shape.prototype.name = 'Shape';
Shape.prototype.toString = function () {
return this.name;
};

function TwoDShape() {}
// take care of inheritance
TwoDShape.prototype = Shape.prototype;
TwoDShape.prototype.constructor...