Add a URL property to the original event object jQuery wraps

jquery-event-url.js

(function($) {
  
  // Capture the original $.Event constructor
  $._Event = $.Event;

  // Override the $.Event constructor (preserve the 2 arguments)
  $.Event = function(src, props) {

    // If the src argument is truthy, add a URL property to it
    if (src) {

      src.URL = window.location.href;
    }

    // Call the original $.Event constructor
    $._Event.call(this, src, props);
  };

  // Make sure the new $.Event prototype matches the old one
  $.Event.prototype = $._Event.prototype;
  
})(jQuery);

// Later on...
$('selector').on('event', function(evt) {
  
  if (evt.originalEvent) {
   
    // Do something with evt.originalEvent.URL
    console.log(evt.originalEvent.URL);
  }
});