Data validation is an essential aspect of any Web application that accepts data from the user.
NET, JSP, and so forth, or you can take advantage of client-side Java Script.Java Script's regular expressions simplifies data validation.Regular expressions are a type of pattern matching.They allow you to easily describe a pattern in text and are a great tool for validating textual data.In addition to pattern matching, they can be used to replace text.Since I was first introduced to regular expressions when working on a UNIX system via Perl, support for regular expressions has greatly expanded.
One note: If you spend a lot of time around other developers, you may hear regular expressions referred to as Reg Ex or Reg Exp.
While both are powerful, regular expression syntax is a bit arcane and can take a while to master.
Let's take a closer look at the basics of developing regular expressions. There are entire books devoted to the subject, but I will cover a few of the basics to get you started.
A basic feature is anchors, which allow you to specify the start and/or end of a string.
The caret (^) is used to indicate the beginning of a string, while the dollar sign ($) indicates the end.
You should use an escape sequence if you need to include a caret or dollar sign in a search string.