pass along tracking link

I use a weebly website, so no php or serverside scripting. We use a weebly website. We need to pass along a tracking link to a third party website. Need a java script or something of the sort which will capture the url of the incoming user. And pass it along when/if they go to the third party application form so that they can place in to the application where our user came from. Other solutions are fine, just let me know how they would do it. example [login to view URL] we need to pass along to a third party that ?s=adwords was in the link