Visual QuickStart Guide: JavaScript, Ninth Edition

7. Forms and Regular Expressions

In This Chapter

Validating an Email Address with Regular Expressions

Validating a File Name

Extracting Strings

Formatting Strings

Formatting and Sorting Strings

Formatting and Validating Strings

Replacing Elements Using Regular Expressions

Regular expressions are an amazingly powerful way to validate and format text strings. Using regular expressions, you can write a line or two of JavaScript code that can accomplish tasks that otherwise would have taken several dozen lines.

A regular expression (often abbreviated as RegExp or called by its synonym grep) is a pattern—written using special symbols—that describes one or more text strings. You use regular expressions to match patterns of text so that your script ...