Show HTML elements with duplicated IDs in the console

duplicate-ids.js

// @see http://stackoverflow.com/a/509965/120080
(function ($) {
  $('[id]').each(function () {
    var ids = $('[id="'+this.id+'"]');
    if(ids.length>1 && ids[0]==this) {
      console.warn('Multiple IDs #'+this.id);
      console.group();
      ids.each(function () {
        console.info(this);
      });
      console.groupEnd();
    }
  });
})(jQuery);