SCRIPT5009: 'URLSearchParams' is undefined in IE 11

Odhikari's answer as a (partial) polyfill:

(function (w) {

    w.URLSearchParams = w.URLSearchParams || function (searchString) {
        var self = this;
        self.searchString = searchString;
        self.get = function (name) {
            var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(self.searchString);
            if (results == null) {
                return null;
            }
            else {
                return decodeURI(results[1]) || 0;
            }
        };
    }

})(window)

If anyone finds this in 2019, corejs now also supports URLSearchParams as a polyfill, so you can just stay with corejs and don't have to brew together something yourselves.

import 'core-js/features/url-search-params';

https://github.com/zloirock/core-js#url-and-urlsearchparams

Got a solution by replacing the code with the following:

$.urlParam = function(name){
    var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
    if (results == null){
       return null;
    }
    else {
       return decodeURI(results[1]) || 0;
    }
}

So for example "example.com?param1=name&param2=&id=6"

$.urlParam('param1');  // name
$.urlParam('id');      // 6
$.urlParam('param2');  // null