Chapter 14 - A Brief Look at JavaScript

If a popup window mysteriously appears while you are surfing the Web, you’re experiencing the effects of JavaScript. JavaScript is a scripting language and JavaScript commands can be included in an XHTML file.

Using JavaScript, you can incorporate techniques and effects that will make your Web pages come alive! You can display an alert box containing an important message for the user. You can display an image when a user moves the mouse pointer over a link, and much more. You don’t have to be a programmer in order to be able to add a little sizzle to your Web pages. This chapter introduces JavaScript and some of its capabilities, and provides some samples that you can build on to create your own Web pages.

JavaScript Resources

• Beginning JavaScript Tutorials
• JavaScript Tutorial for the Total Non-Programmer
• More Beginning JavaScript Tutorials
• Core JavaScript 1.5 Reference Manual
• The JavaScript Source

Chapter Updates

Thank you to Elizabeth Drake, at Sante Fe Community College for mentioning the following issue:

Page 603, Exercise 5 will not initially work the way you expect!
JavaScript assumes the two values you entered are strings and concatenates them instead of adding them.

Suggested solution hint:
As you accept each value in a prompt, use the parseInt()function to convert each value to an number stored as a integer data type in memory. Reference

Extension:
Use the isNAN()function to verify that a numeric value was entered before invoking parseInt(). Reference

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