ajaxurl JS variable can be used for the WP admin ajax URL in any JS file of the RealHomes theme now.

ajaxurl-use-example.js

var add_to_favorite_options = {
    type : 'post',
    url : ajaxurl, // This is how we can use the 'ajaxurl' variable for the WordPress ajax URL.
    data : {
      action: 'add_to_favorite',
      property_id : propertyID,
    },
    success: function(response) {
      if('false' !== response) {
        $(favorite_link).addClass('hide');
        $(span_favorite).delay(200).removeClass('hide');
      }
    }
  };
  $.ajax(add_to_favorite_options);