Web Marketing Resources Home
Web Marketing Articles
Search Engine Optimization
Free
Training
Marketing Jokes
Current Issue
Back Issues
John's Articles
Free
Search Engine Marketing & Optimization Tools:
Keyword
Suggest
Keyword
Density
Keyword
Typos
PageRank Search
Future
PageRank
Link
Popularity
|
Validating Credit Card
Numbers
On-The-Fly
by Will Bontrager
If
you collect credit cards on your site, the JavaScript presented with this
article can save a lot of frustration.
* If you collect and send credit card information
to a payment gateway:
The JavaScript can spot typographical errors before connecting your customer to
the gateway. If your customer types a "7" instead of a "6,"
for example, the JavaScript will know something is wrong. You can allow your
customer to correct the credit card number before getting a "credit card
declined" message.
* If you collect and store credit card information on your secure server for
later processing:
The JavaScript can spot typographical errors in the credit card number before
you try to process it. Correcting the number right then and there can save you
the time otherwise spent trying to contact the customer to get the right number.
Note: The JavaScript does not test whether or not the credit card
itself is good. It just tests the number.
The JavaScript uses the Mod-10 algorithm to validate credit card numbers. It can
also identify credit card types (MC, Visa, and so forth).
The Mod-10 algorithm is a special method of adding up the digits of a credit
card number (reverse the order of the digits, multiply every other digit by 2,
add together all of the resulting digits) and then dividing the result by 10. If
the remainder is zero, the number passes. Otherwise, it fails.
The Mod-10 process is described in the article, "Creating a Credit Card
Validation Class With PHP" by Mitchell Harper, available as of this writing
at http://www.webmasterbase.com/article/728
The JavaScript has customization instructions. It's only four steps:
1. What message to display if the credit card number
doesn't pass the Mod-10 algorithm.
2. What message to display if the credit card type is
unknown.
3. What message to display if the type is unknown and
the Mod-10 fails.
4. Whether or not to display a message when the credit
card passes the tests.
The JavaScript is free to use from the demo page. Use your browser's "view
source" to get the code or download the zip file. The URL is
http://willmaster.com/a/14/pl.pl?145d
All of the JavaScript functions go into the HEAD area of your web page.
Give it a try. I think you'll find it useful.
For advanced users, the JavaScript functions provide values for three different
variables. You can retrieve and use the values in your own JavaScript or CGI
programs. The values are:
1. The name of the credit card as determined by the
credit card number provided.
2. Whether or not the credit card number is of a valid
format (passed the Mod-10 test).
3. The credit card number that was checked, minus any
spaces, hyphens, and other
non-numeric characters
the user might have typed.
More information is presented in the source code, as comments.
http://willmaster.com/a/14/pl.pl?145d
Copyright 2002
Bontrager Connection, LLC
"WillMaster Possibilities" ezine http://willmaster.com/possibilities/
mailto:[email protected]
Make
your websites do more than just show text and pretty pictures and tap into the
mother lode of free and low-cost Internet CGI applications available on
the Net, putting them to work for you and your online enterprise.
The catch? You'll need to know how to install
them on your server. William
Bontrager shows you how.
|
|
|