How can i pass multiple values of fropdowns in url?

How can i pass multiple values of fropdowns in url?

Hey guys, 
I'm currently creating a project with Codeigniter and i have some dropdowns which will filter my db results using "GET" method in url.

What i want is to pass or replace (if its already in the url) the value of the selected dropdowns ONLY, like an array.

A guy helped me on some point but on selecting another dropdown box the value in url is replaced with the last chosen. Could you please help me on that?!

P.S.: If you faced the same (filtering results) and you have a different proposal on how to achieve this, please do it freely!!

Thank you!!

MyJquery code:
  2.   $('#filters select').change(function(){
  3.       let filters = [];
  4.       $('#filters select').each(function(){
  5.           const string = $(this).attr('id');
  6.           const value = $(this).val();
  7.           if(value != '') {
  8.             filters.push(string + '=' + value);
  9.           }
  10.       });
  11.       window.location.search = filters.join('&');
  12.   });



My html dropdowns code: 
  2. <div class="col-lg-2" id="filters">
  3. <div class="form-group mt-3">
  4.           <select class="form-control filter-selection" id="petStatus">
  5.             <option value="">-- Status --</option>
  6.             <option value="1">Lost</option>
  7.             <option value="2">Found</option>
  8.           </select>
  9.         </div>

  11.         <div class="form-group input-group">
  12.           <select class="form-control filter-selection" id="petType">
  13.             <option value="">-- Choose type --</option>
  14.             <option value="1">Cat</option>
  15.             <option value="2">Dog</option>
  16.             <option value="3">Other</option>
  17.           </select>
  18.         </div>
  19. </div>