Inserting Affiliate Codes Into Links and Forms
By William Bontrager
If you have your own affiliates, you may wish to insert affiliate codes into links and forms. Reasons for doing this might include
1. Tracking an affiliate code from page to page.
2. Pre-filling in an affiliate code into a form text or hidden field, to
Receive the affiliate code via email.
Record the affiliate code in a database.
Email an affiliate URL to someone else.
Have the affiliate code available when processing the rest of the submitted information.
3. Redirecting the site visitor to a different page, customized for the affiliate code.
The Web Page URL
In order to use the affiliate code in links and forms, the URL of the web page in the user's browser must be followed by either a question mark or a hash mark ("?" or "#") and then the affiliate code. Without those, the JavaScript presented in this article won't have an affiliate code to process.
Here are examples of what I mean:
http://WillMaster.com/page.html?AF33
http://WillMaster.com/page.html#AF33
In both of those examples, the affiliate code is "AF33". In one, the affiliate code is appended to the URL with a question mark and in the other it is appended with a hash mark.
Domain URLs (without specifying a particular web page) can also have the affiliate code appended. Examples:
http://WillMaster.com/?AF33
http://WillMaster.com/#AF33
Notice that a slash character follows the domain name. The slash is necessary for some browsers to properly translate the URL.
The Affiliate Code Extractor
The following eleven lines of JavaScript, when placed in the HEAD section of your web page, will extract the affiliate code from the web page URL:
<script type="text/javascript" language="JavaScript"><!--
function GetAffiliateCode() {
var DefaultAffiliateCode = 'mydefaultcode';
var thisurl = location.href;
var ql = thisurl.indexOf('?
if(ql < 0) { ql = thisurl.indexOf('# }
if(ql >= 0) { return thisurl.substr(ql + 1); }
return DefaultAffiliateCode;
}
ThisAffiliateCode = GetAffiliateCode();
//--></script>
In the third line of the above JavaScript, you can specify a default affiliate code to use when the web page URL doesn't provide one. If you want a blank or null affiliate code for the default, remove all text between the two apostrophes (but keep the apostrophes).
Line by line, the above JavaScript:
Line 1 -- Tells the browser that the following lines are JavaScript.
Line 2 -- Begins function GetAffiliateCode().
Line 3 -- Stores a default affiliate code into variable DefaultAffiliateCode.
Line 4 -- Stores the URL in the browser's address bar into variable thisurl.
Line 5 -- Stores the location of the question mark in the URL into variable ql.
Line 6 -- If the URL has no question mark, store the location of the hash mark into variable ql.
Line 7 -- If the URL had a question mark or a hash mark, returns all the text in the URL that follows the mark.
Line 8 -- This line runs only if there was no question mark or hash mark in the URL. It returns the default affiliate code.
Line 9 -- Marks the end of function GetAffiliateCode().
Line 10 -- Runs function GetAffiliateCode() and stores the value the function returns into variable ThisAffiliateCode. Variable ThisAffiliateCode can now be used to insert the affiliate code into links and forms.
Line 11 -- Tells the browser that the lines of JavaScript end here.
Inserting Affiliate Codes Into a Link
If you insert the affiliate code into your intra-site links, so the affiliate code is appended to the URL with either a question mark or a hash mark, you'll be able to send the affiliate code with the visitor, from page to page, without the use of cookies.
Inserting the affiliate code can be done with JavaScript. This is an overview of how to do it:
For more information,
[anchor tag link goes here]
Click Here</a>
Not all browsers are JavaScript-enabled. If it's important that default HTML is inserted even when JavaScript isn't available for a browser, then use the NOSCRIPT tag to specify the HTML for that contingency.
Here is a working example of JavaScript to insert an affiliate code into a link. The affiliate code is appended to a hash mark -- the affiliate code being that which the JavaScript in the HEAD area extracted when the page was being loaded:
For more information,
<script type="text/javascript" language="JavaScript"><!--
document.write('<a href="http://mydomain.com/page.html#');
document.write(ThisAffiliateCode);
document.write('">');
//--></script>
<noscript>
<a href="http://mydomain.com/page.html">
</noscript>
Click Here</a>
document.write() prints the content between the parenthesis.
If you're printing a string of characters, enclose the characters between apostrophes or quotation marks. Whatever you decide to enclose the characters with, if you use the same character as one of the characters that are to be printed, precede the character with a backslash. Example:
document.write('He\'s back!');
To print the contents of a variable, put the variable between the parenthesis, not enclosed with apostrophes or quotation marks.
Inserting Affiliate Codes Into a Form
Any form processed by a script that allows custom fields can have affiliate codes inserted into form field values. For example, this will take the affiliate code extracted from the URL and insert it into a hidden filed named "afc":
<script type="text/javascript" language="JavaScript"><!--
document.write('<input type="hidden" name="afc" value="');
document.write(ThisAffiliateCode);
document.write('">');
//--></script>
<noscript>
<input type="hidden" name="afc" value="something">
</noscript>
That hidden field can be processed by the form's CGI program just like any other custom hidden field. If the program can update a database with form field names, like Master Form [http://willmaster.com/master/form/] can do, then the affiliate code might be used to measure performance or other statistics.
If you're providing "recommend this site" forms and want your affiliate's code to be part of the recommended URL, the hidden field representing the URL being recommended can be modified to append the affiliate code with either a question mark or a hash mark. Here is an implementation example for use with Master Recommend Pro [http://willmaster.com/master/recommendpro/] :
<script type="text/javascript" language="JavaScript"><!--
document.write('<input type="hidden" ');
document.write(' name="siteURL" ');
document.write(' value="http://mydomain.com/page.html#');
document.write(ThisAffiliateCode);
document.write('">');
//--></script>
<noscript>
<input type="hidden"
name="siteURL"
value="http://mydomain.com/page.html">
</noscript>
For Master Recommend [http://willmaster.com/master/recommend/] (the free version) replace "siteURL" with "siteurl" in both places.
If you want to offer a form field where the user can type in the affiliate code (or sponsor's code, as in the example), yet pre-fill in the code whenever possible, do something like this:
Your sponsor's code:
<script type="text/javascript" language="JavaScript"><!--
document.write('<input type="text" name="afc" value="');
document.write(ThisAffiliateCode);
document.write('">');
//--></script>
<noscript>
<input type="text" name="afc" value="something">
</noscript>
Redirecting To a Customized Page
If you have a CGI program that generates customized pages with affiliate information embedded in it, the following code can redirect the site visitor to the CGI script. The affiliate code is sent to the script, which allows the script to customize the page for the visitor.
<script type="text/javascript" language="JavaScript"><!--
var URL = 'http://mydomain.com/cgi-bin/script.cgi?' +
ThisAffiliateCode;
location.href = URL;
//--></script>
Notice that there is no NOSCRIPT tag here. If the browser is JavaScript-disabled, the page would not be redirected and everything on the original page would be displayed, whether or not it is between NOSCRIPT tags.
To load faster in JavaScript-enabled browsers, you might put all of the rest of the page between NOSCRIPT tags. This would enable the browser to ignore images and tables and such, and run the JavaScript redirection code sooner.
Will Bontrager
About the Author:
William Bontrager Programmer/Publisher, "WillMaster Possibilities" ezine mailto:[email protected]
Are you looking for top quality scripts? Visit Willmaster [http://hop.clickbank.net/hop.cgi?nturavets/willmaster] and check out his highly acclaimed Master Series scripts. Some free, some for a fee.
CGI Security Issues
By Richard Lowe
When you are creating or using CGI routines, you must be careful to keep good coding techniques, security and just plain common sense in mind. Sometimes you can do things that cause serious unexpected site effects. In fact, sometimes you may think you are making your CGI routine secure only to find out it just doesn't work like you expected.
A good example of a this phenomenon is a simple CGI routine called FormMail. This was written a number of years ago by a fellow named Matt Wright to allow data to be entered in a form, then emailed to a recipient.
I first looked at FormMail because I wanted to cut down on spam. You see, my web site had my email address embedded on every single page. I thought this was a good idea to allow people to send me an email message when they wanted to contact me. In fact, all of the web design books indicate that all good web sites include an email link of this kind.
I soon discovered, much to my horror, that spammers use special programs called Spam Harvesters to scan websites for email addresses. They add these addresses to their mailing lists and resell them over and over. The result is a large increase in the amount of spam that I received.
After much research, I came to the conclusion that the best defense against spam robots was to simply stop including my email address on my web sites. This left the question of how to allow users to contact me when they had questions or comments.
The answer is simple - use a form. The advantage is that the email address is hidden within the CGI routine or a text file and it is simply not possible for a spam harvester to pick it up. As long as the email address is coded into the CGI routine or in a database you are relatively secure.
However, many people use FormMail in a different way. Let's say you want to allow your visitors to "tell a friend" about your site. So you include a form which allows visitors to enter their message and a target email address. If you are not very careful you could find that you have set yourself up as a spam relay.
You see, spammers are always looking for ways to hide their identity. One common method is to search the internet for occurrences of FormMail. Sometimes I wonder if spammers rub their hands together in glee when they find sites which use FormMail with user-entered email addresses.
The spammer essentially "hijacks" the FormMail CGI routine and causes it to send out emails as fast and furiously as they can. I know of one instance where a spammer sent over one million emails in a single day before someone noticed that their web server was going very slowly (I wonder how long it would have taken had the spammer tried limiting the load on the server so it didn't show up as much).
What happens here is very simple. The FormMail CGI routine is simply called remotely by the spammer, once for each spam email that he wants to send.
Ah, you say, but you could code the FormMail routine to check the referrer field. This would surely prevent a spammer from using it remotely, as his referrer would not be the website URL.
Sorry, no. The referrer field is actually a text string passed to the CGI routine by the browser. The spammer is most likely using a program which appears, to your web site, to be just another browser. Since the spammer controls the program he can code it to send the CGI routine whatever value he wants for the referrer field.
As it turns out, it is very difficult to make a CGI routine such as FormMail even relatively secure, and it may be impossible to make it bullet-proof. All you can do is check enough things and put in delays here and there to slow down and discourage spammers.
You could, for example, only allow one posting per IP address per hour. You could also check referrer just to block out the more ignorant spammers. I suppose you could count the number of times the routine is called, and have it just stop working after a certain amount. For example, only allow one hundred calls per day from anywhere.
The point here is not to tear apart the FormMail routine. The goal is to show how difficult it can be to make anything secure on the internet, and demonstrate that some assumptions (that the referrer field is a valid check) may not be true in all cases.
What do you do? Before you implement any CGI or similar interface, be sure and do a little research to be sure you completely understand and handle the ramifications. If you don't do this, you may find yourself the victim of a hacker or spammer.
About the Author
Richard Lowe Jr. is the webmaster of Internet Tips And Secrets at http://www.internet-tips.net - Visit our website any time to read over 1,000 complete FREE articles about how to improve your internet profits, enjoyment and knowledge.
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