Dynamically change URL query parameters on button clicks via JavaScript [duplicate]

I am using the below script to dynamically change links with query parameters. The links are dynamically changed when I click on the button.

example.com/abc?client_id=123

The problem is when a user lands on the site with this URL from Google Ads - example.com/abc?gclid_id=786, and then clicks on the button the URL is dynamically changed to example.com/abc?gclid=786?client_id=123

I want it example.com/abc?gclid=786&client_id=123

Can I modify the existing script if the users come from Google change the parameter to &client_id=123 and when the user comes organically change the script to ?client_id=123

The parameter values are dynamic and they are mapped with cookie values (This is sorted). The main problem is & and ?

<script>

(function () {


var links = document.querySelectorAll('a[href*=abc]');
  
var clientId = '?client_id={{Read Cookie Value}}'

links.forEach(function(link) {
              
var original = link.getAttribute('href');
link.setAttribute('href', original+clientId)
              
              
              
 })


}) ();
  
</script>