pos_product_template DOM error about pos HOT 8 CLOSED

`init: function(parent, options) {
            var self = this;
            this.attribute_list = [];
            this.product_template = null;
            this.click_set_attribute_handler = function(event){
                /*TODO: Refactor this function with elegant DOM manipulation */
                // remove selected item
                parent = this.parentElement.parentElement.parentElement;
                parent.children[0].classList.remove('selected');
                for (var i = 0 ; i < parent.children[1].children[0].children.length; i ++){
                    elem = parent.children[1].children[0].children[i];
                    elem.children[0].classList.remove('selected');
                }
                // add selected item
                this.children[0].classList.add('selected');
                self.__parentedParent.variant_list_widget.set_filter(this.dataset['attributeId'], this.dataset['attributeValueId']);
            };
            this.click_reset_attribute_handler = function(event){
                /*TODO: Refactor this function with elegant DOM manipulation */
                // remove selected item
                parent = this.parentElement;
                parent.children[0].classList.remove('selected');
                for (var i = 0 ; i < parent.children[1].children[0].children.length; i ++){
                    elem = parent.children[1].children[0].children[i];
                    elem.children[0].classList.remove('selected');
                }
                // add selected item
                this.classList.add('selected');
                self.__parentedParent.variant_list_widget.reset_filter(this.dataset['attributeId']);
            };
            this._super(parent, options);
        },`