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Object-Oriented JavaScript - Second Edition

You're reading from   Object-Oriented JavaScript - Second Edition If you've limited or no experience with JavaScript, this book will put you on the road to being an expert. A wonderfully compiled introduction to objects in JavaScript, it teaches through examples and practical play.

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Product type Paperback
Published in Jul 2013
Publisher Packt
ISBN-13 9781849693127
Length 382 pages
Edition 2nd Edition
Languages
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Toc

Table of Contents (14) Chapters Close

Preface 1. Object-oriented JavaScript 2. Primitive Data Types, Arrays, Loops, and Conditions FREE CHAPTER 3. Functions 4. Objects 5. Prototype 6. Inheritance 7. The Browser Environment 8. Coding and Design Patterns A. Reserved Words B. Built-in Functions
C. Built-in Objects D. Regular Expressions
Index

Copying properties


Now, let's try a slightly different approach. Since inheritance is all about reusing code, can you simply copy the properties you like from one object to another? Or from a parent to a child? Keeping the same interface as the preceding extend() function, you can create a function extend2() which takes two constructor functions and copies all of the properties from the parent's prototype to the child's prototype. This will, of course, carry over methods too, as methods are just properties that happen to be functions.

function extend2(Child, Parent) {
var p = Parent.prototype;
var c = Child.prototype;
for (vari in p) {
c[i] = p[i];
}
c.uber = p;
}

As you can see, a simple loop through the properties is all it takes. As with the previous example, you can set an uber property if you want to have handy access to parent's methods from the child. Unlike the previous example though, it's not necessary to reset the Child.prototype.constructor because here the child prototype is augmented...

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