JavaScript: Introduction to Scripting

Chapter 6

JavaScript: Introduction to Scripting

Introduction

In the first five chapters, we introduced the Internet and Web, web browsers, Web 2.0, XHTML and Cascading Style Sheets (CSS). In this chapter, we begin our introduction to the JavaScript¹ scripting language, which facilitates a disciplined approach to designing computer programs that enhance the functionality and appearance of web pages.

In Chapters 6–11, we present a detailed discussion of JavaScript—the de facto stan-dard client-side scripting language for web-based applications due to its highly portable nature. Our treatment of JavaScript serves two purposes—it introduces client-side scripting (used in Chapters 6–13), which makes web pages more dynamic and interactive, and it provides the programming foundation for the more complex server-side scripting presented later in the book.

We now introduce JavaScript programming and present examples that illustrate sev-eral important features of JavaScript. Each example is carefully analyzed one line at a time. In Chapters 7–8, we present a detailed treatment of program development and program control in JavaScript.

Before you can run code examples with JavaScript on your computer, you may need to change your browser’s security settings. By default, Internet Explorer 7 prevents scripts on your local computer from running, displaying a yellow warning bar at the top of the window instead. To allow scripts to run in files on your computer, select Internet Options from the Tools menu. Click the Advanced tab and scroll down to the Security section of the Settings list. Check the box labeled Allow active content to run in files on My Computer (Fig. 6.1). Click OK and restart Internet Explorer. XHTML documents on your own computer that contain JavaScript code will now run properly. Firefox has JavaScript enabled by default.