title: Taking a URL and adding /?var0=val0&var1=val1 with out leaving the page and no user input
body: <p>OK - Thanks for taking the time! </p>
  
  <p>I am using WP on a CentOS 6 server. I have a plug in with the functions, I have a function that makes a DB call and populates relevant products based on $_GET  variables, I took from one of the other project and modify it so it works! But here where I run in to the problem, I go to the main page and i have a function that gets called first, goes through the URL name and determines the categories id and then from that I need to pass that to the URL so that when the next function then calls $_GET["category_id"] and that ID  is there and ready to be use and it it does its magic. (all staying on the same page no refreshing or anything) </p>
  
  <p>So I need to put that on the URL as the page is being loaded and so that I can use it (Again i get the variables from a function that is doing all the work with the address for relevant info,) So how do i do it? HTML or PHP, and a straight forward way no extra installs would be nice :) </p>
  
  <p>Edit 1:
  So is there something then I could integrate in that would be simple and straight forward that would allow me to do a mini refresh and get the right variables in place, never used JavaScript but seams to be getting or something in php ... Ideas are welcome :) </p>