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Learning JavaScript by Shelley Powers

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Input Fields and JiT Regular Expressions

Most form fields just require some text without giving any concern to the format. However, certain types of fields may require a specific format. Rather than send the data across to the server to see if the data is valid, we’ll use regular expressions to validate the format of the data, at a minimum, first.

Using regular expressions, as defined in Chapter 3, some of the more common validations are with the following fields:

  • Warranty or purchase certificates

  • Email addresses

  • Phone numbers

  • Social Security numbers or other forms of identification

  • Dates

  • State abbreviations

  • Credit card numbers

  • Web page URLs or other forms of URI (uniform resource identifiers)

Rather than try out various regular expressions directly in code, Example 7-5 contains a little application, the JiT RegEx Machine, that takes a regular expression typed in one field, a string in another, and then does a pattern match when the form is submitted. The results are output to a third field.

Example 7-5. The JiT RegEx Machine application

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <title>The JiT RegEx Machine</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <script type="text/javascript"> //<![CDATA[ if (window.addEventListener) { window.addEventListener("load",setupEvents,false); } else if (window.attachEvent) { window.attachEvent("onload", setupEvents); } else { window.onload=setupEvents; ...

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