+ sortShelfBooks(sortProperty) {
+ const books = Array.from(this.shelfBookList.children);
+ const reverse = sortProperty === this.lastSort;
+
+ books.sort((bookA, bookB) => {
+ const aProp = bookA.dataset[sortProperty].toLowerCase();
+ const bProp = bookB.dataset[sortProperty].toLowerCase();
+
+ if (reverse) {
+ return bProp.localeCompare(aProp);
+ }
+
+ return aProp.localeCompare(bProp);
+ });
+
+ for (const book of books) {
+ this.shelfBookList.append(book);
+ }
+
+ this.lastSort = (this.lastSort === sortProperty) ? null : sortProperty;
+ this.onChange();
+ }
+
+}