Regular Expressions and JavaScript

About 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, 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. By learning and using these operators, you’ll be able to save yourself a huge amount of effort whenever you need to detect and manipulate text strings.

About the RegExp Object

JavaScript has a built-in RegExp object that’s automatically set (and reset) every time a script executes a regular expression method (given in Table 4 and 5). The properties of this object are shown in Table 3 and its methods in Table 4. The RegExp object isn’t a variable that contains the result of the regular expression operation, but rather it contains the pattern described by the regular expression, in a form that can be used in your scripts via the RegExpobject’s properties and methods.

Reference: Chapter 7 of JavaScript Visual QuickStart Guide (8th Edition)