JSFiddle - React, Tailwind, and code Playground

HTML

<label class="setit" onclick="javascript:setbox('value',this);"> 
<INPUT value="value" type=checkbox name=ds>value</label>

JavaScript

var url=""; 
 function onloadbody(seturl){ 
     url = window.location.href; 
     url += "&"; 
     url += seturl; 
     alert(url); 
 } 
  
 function setbox(ulica,box){ 
  if (box.checked){
   url = url.split("q="+ulica)[0] + url.split("q="+ulica)[1];
   alert(url);
  }else{
   //works
  }  
 }