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

Using a mix of prototypal inheritance and copying properties


When you use inheritance, you will most likely want to take already existing functionality and then build upon it. This means creating a new object by inheriting from an existing object and then adding additional methods and properties. You can do this with one function call, using a combination of the last two approaches just discussed.

You can:

  • Use prototypal inheritance to use an existing object as a prototype of a new one

  • Copy all of the properties of another object into the newly created one

    function objectPlus(o, stuff) {
    var n;
    function F() {}
    F.prototype = o;
    n = new F();
    n.uber = o;
    
    for (vari in stuff) {
    n[i] = stuff[i];
    }
    return n;
    }

This function takes an object o to inherit from and another object stuff that has the additional methods and properties that are to be copied. Let's see this in action.

Start with the base shape object:

var shape = {
name: 'Shape',
toString: function () {
return this.name;
}
};

Create a 2D object...