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

What is a function?


Functions allow you to group together some code, give this code a name, and reuse it later, addressing it by the name you gave it. Let's see an example:

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

The parts that make up a function are shown as follows:

  • The function statement.

  • The name of the function, in this case sum.

  • The function parameters, in this case a and b. A function can take any number of parameters, separated by commas.

  • A code block, also called the body of the function.

  • The return statement. A function always returns a value. If it doesn't return a value explicitly, it implicitly returns the value undefined.

Note that a function can only return a single value. If you need to return more values, you can simply return an array that contains all of the values you need as elements of this array.

The preceding syntax is called a function declaration. It's just one of the ways to create a function in JavaScript, and more ways are coming up.

Calling a function

In order...