Custom action for required attribute in HTML5 Forms

gist.js

	document.addEventListener("DOMContentLoaded", function() {
    var elements = document.getElementsByTagName("INPUT");
    for (var i = 0; i < elements.length; i++) {
      elements[i].oninvalid = function(e) {
      	var start = new Date().getTime();
      	for(var i = 0; i < e.path.length; i++) {
      		if(e.path[i]['classList']) {
      			var parentClass = jQuery.inArray('postbox-container', e.path[i]['classList']);
      			if(parentClass != -1) {
      				if(e.path[i]['classList'][parentClass]) {
								var container = jQuery('#postbox-container-2').children().children();
								var itemId = e.path[i]['previousElementSibling'];
								console.log('item id: ', itemId);
								jQuery(container).css('display', 'none');
								//jQuery()
							}
      			}
      		}
      	}
      	var end = new Date().getTime();
				var time = end - start;
				console.log('Execution time: ', time);

      	//console.log('parent class: ', e.path);
      	var parentClass = jQuery.inArray('document', e.path);
      	//console.log('parent class: ', parentClass);
        e.target.setCustomValidity("");
        if (!e.target.validity.valid) {
          e.target.setCustomValidity("This field cannot be left blank");
        }
      };
      elements[i].oninput = function(e) {
        e.target.setCustomValidity("");
      };
    }
	})