Book Image

Object-Oriented JavaScript - Second Edition - Second Edition

Book Image

Object-Oriented JavaScript - Second Edition - 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
About the Authors
About the Reviewer
Built-in Functions
Regular Expressions


JavaScript functions are objects. They can be defined using the Function constructor, like so:

var sum = new Function('a', 'b', 'return a + b;');

This is a (generally not recommended) alternative to the function literal (also known as function expression):

var sum = function (a, b) {
  return a + b;

Or, the more common function definition:

function sum(a, b) {
  return a + b;

The Function.prototype members



apply(this_obj, params_array)

Allows you to call another function while overwriting the other function's this value. The first parameter that apply() accepts is the object to be bound to this inside the function and the second is an array of arguments to be send to the function being called.

function whatIsIt(){
  return this.toString();
> var myObj = {};
> whatIsIt.apply(myObj);
"[object Object]"
> whatIsIt.apply(window);
"[object Window]"

call(this_obj, p1, p2, p3, ...)

The same as apply() but accepts arguments one by one, as opposed to as one array.


The number of parameters the function expects.

> parseInt.length;

If you forget the difference between call() and apply():

> Function.prototype.apply.length;

The call() property's length is 1 because all arguments except the first one are optional.

ECMAScript 5 additions to a function




When you want to call a function that uses this internally and you want to define what this is. The methods call() and apply() invoke the function while bind() returns a new function. Useful when you provide a method as a callback to a method of another object and and you want this to be an object of your choice.

> whatIsIt.apply(window);
"[object Window]"