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

Conditions and loops


Conditions provide a simple but powerful way to control the flow of code execution. Loops allow you to perform repetitive operations with less code. Let's take a look at:

  • if conditions

  • switch statements

  • while, do-while, for, and for-in loops

Note

The examples in the following sections require you to switch to the multiline Firebug console. Or, if you use the WebKit console, use Shift + Enter instead of Enter to add a new line.

The if condition

Here's a simple example of an if condition:

var result = '', a = 3;
if (a > 2) {
  result = 'a is greater than 2';
}

The parts of the if condition are:

  • The if statement

  • A condition in parentheses—"is a greater than 2?"

  • A block of code wrapped in {} that executes if the condition is satisfied

The condition (the part in parentheses) always returns a Boolean value, and may also contain the following:

  • A logical operation: !, &&, or ||

  • A comparison, such as ===, !=, >, and so on

  • Any value or variable that can be converted to a Boolean...