I work at a company that has many clients that have their own website that "plugs in" to our system. In other words they have their own website and they have a link that, when the user clicks it, transitions them over to our site.

There is a feature that I want to track by giving the client a small block of code to put on their homepage. Whenever the homepage is loaded with a certain query string variable I want the block of code to request a file on my server. Then on the server I'll record the tracking info based on the query string.

All this would be really easy if I can guarantee that the client would be using jQuery or some similar library, but there are a lot of clients and I can't really rely on them all using jQuery. At the same time I'd like to limit the size of the block of javascript code that they paste in.

I think the best solution would be to have something like:

if(querystring.substring("Tracking=") > 0)
{
   include("blah.aspx?TrackingQS=" + querystring);
}

but I can't find a include function in built-in javascript without calling some library like jQuery.

Any thoughts?? I could do straight up AJAX but I want to limit the number of lines of code for several reasons that I won't bore you with here.