Adding Attribute to HTML Tag <a href=

[nothing1]

Ok here is my question i hope its something easy. I have CMS that generates images from whatever url I put with its corresponding syntax. Well I want to add a Lightbox to does images but instead of going into the CMS to find how where it outputs the actual code that appears i was thinking of using JS to add an attribute of rel="lightbox" to links within a certain div that have a class of media.

Example:
Here is a link to an image that might be found on my page

[HTML]<a href="images/blah.jpg" target="_self" class="media"><img src="images/blah.jpg" /></a>[/HTML]

One way I was thinking of doing it was the function "replace". something like this

javascript:document.body.innerHTML.replace("Index","67890");

and then this code to find the class which im not sure if it will work.

//Create an array 
var allPageTags = new Array(); 
 
function doSomethingWithClasses(theClass) {
//Populate the array with all the page tags
var allPageTags=document.getElementsByTagName("*");
//Cycle through the tags using a for loop
for (i=0; i<allPageTags.length; i++) {
//Pick out the tags with our class name
if (allPageTags[i].className==theClass) {
//Manipulate this in whatever way you want
allPageTags[i].style.display='none';
}
}
} 

Can someone please help me put this together. My final link should output as.
[HTML]<a href="images/blah.jpg" target="_self" class="media" rel="lightbox"><img src="images/blah.jpg" /></a>[/HTML]

[nothing1]

Looking over the Javascript code for getElementByClass it seems like i might not even need the replace function if the getElementByClass code work by replacing the "style.display="none"" to something else right? how do i set a rel?

Please note that im a total Noob at Javascript im more of a php guy.

[acoder]

Try:

allPageTags[i].setAttribute("rel","lightbox");

[nothing1]

thanx! worked perfectly.

[acoder]

You're welcome. Glad it worked.