/**
  * Advanced SEO Technique for Affiliate Marketing Links
  * Copyright 2010, Darren Slatten, http://www.SEOmofo.com/
  * 
  * The following code consists of 2 functions. The first 
  * function is a utility function that requires 2 parameters:
  * an element name and a CSS class name. It checks to see if
  * the specified element (e) is a member of the specified class (c),
  * and returns true or false. The element name can be either an
  * id or a tag name. The class name can either be the only class
  * assigned to the element OR it can be one of several CSS classes
  * assigned to the element. This function is used by the second
  * function.
  * 
  * The second function finds all <span> elements that have "affiliate"
  * as one of their CSS classes and then turns them into affiliate
  * links.
  * 
  */



// Utility function for checking if an element (e) is a member of CSS class (c).
function hasClass(e, c) {

// If we passed the function a string, then get the element with that id.
	if (typeof e == "string") e = document.getElementById(e);

// Declare the variable "classes" as the text value of our element's CSS classes.
	var classes = e.className;

// If our element doesn't have any CSS classes assigned to it, return false.
	if (!classes) return false;

// If our element has exactly one class and that class is (c), return true.
	if (classes == c) return true;

// If our element has multiple classes and one of them is (c), return true.
	return e.className.search("\\b" + c + "\\b") != -1;
};



// Function for rendering affiliate links in a way that won't pass PageRank.
function affiliateLinks(){

// Declare local variables.
	var theURL, theAnchorText, theTitle;

// Declare the variable "spans" as the collection of all <span> elements.
	var spans = document.getElementsByTagName('span');

// Perform the following steps for every <span> element.
	for (var i = 0; i<spans.length; i++){

// If the <span> element is part of the "affiliate" class...
		if (hasClass(spans[i], 'affiliate')){

// Use the content between the <span> tags as our affiliate link's anchor text.
// Example: <span class="affiliate" title="Affiliate Site">this will be our anchor text</span>
// The content doesn't have to be just text; it can be HTML too.
// Example: <span class="affiliate" title="Affiliate Site"><img src="/banners/affiliate-logo.png" /></span>
			theAnchorText = spans[i].innerHTML;

// Get the value of the <span> element's title attribute, make it lowercase, and remove whitespace
// characters from the beginning and end.
			theTitle = spans[i].title.toLowerCase().replace(/^\s+|\s+$/g,"");

// Check the value of the <span> element's title attribute against the following possibilities.
			switch (theTitle) {

// If the <span> element's title is "thesis" then set our affiliate link's href to
// "http://www.seomofo.com/affiliate/thesis/"
				case 'provillus': theURL = 'http://www.provillusstore.com/recommends/hww'; break;

// If the <span> element's title doesn't match any of the possibilities I've provided, then make
// my affiliate link do NOTHING when clicked on, because I f***ed up my code somewhere.
				default: theURL = 'javascript: void(0)';
			}

// Insert the new affiliate link into its corresponding <span> element and copy the <span> element's
// CSS classes (all of them) into the affiliate link's <a> tag.
			spans[i].innerHTML = '<a href="' + theURL + '" class="' + spans[i].className + '" style="text-decoration: underline;color:blue">' + theAnchorText + '</a>';

// Remove the title attribute from the <span> element, to prevent Firefox from displaying it in a tooltip.
			spans[i].removeAttribute('title');
		}
	}
}



// Call the affiliateLinks function AFTER the document has finished loading.
window.onload = function(){
	affiliateLinks();
}