JSFiddle - React, Tailwind, and code Playground

HTML

Value of 'first': <span id='value-of-first'></span>

JavaScript

var get_params = function(search_string) {

  var parse = function(params, pairs) {
    var pair = pairs[0];
    var parts = pair.split('=');
    var key = decodeURIComponent(parts[0]);
    var value = decodeURIComponent(parts.slice(1).join('='));

    // Handle multiple parameters of the same name
    if (typeof params[key] === "undefined") {
      params[key] = value;
    } else {
      params[key] = [].concat(params[key], value);
    }

    return pairs.length == 1 ? params : parse(params, pairs.slice(1))
  }

  // Get rid of leading ?
  return search_string.length == 0 ? {} : parse({}, search_string.substr(1).split('&'));
}


$(function() {
   var params = get_params("?first=1&second=2");
    
   $("#value-of-first").html(params["first"]);
});