Javascript for the World Wide Web: Visual Quickstart Guide, Fifth Edition

Chapter 9. Forms and 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) is a pattern, written using special symbols, which describes one or more text strings. You use regular expressions to match patterns of text, so that your script can easily recognize and manipulate text. Like an arithmetic expression, you create a regular expression by using operators, in this case operators that work on text, rather than numbers. There are many regular expression operators, and we'll look at some of the ...