wip(js): add head.html and assets/js

assets/js/modules/components/category-collapse.js

@@ -0,0 +1,36 @@
+/**
+ * Tab 'Categories' expand/close effect.
+ */
+
+import 'bootstrap/js/src/collapse.js';
+
+const childPrefix = 'l_';
+const parentPrefix = 'h_';
+const children = document.getElementsByClassName('collapse');
+
+export function categoryCollapse() {
+  [...children].forEach((elem) => {
+    const id = parentPrefix + elem.id.substring(childPrefix.length);
+    const parent = document.getElementById(id);
+
+    // collapse sub-categories
+    elem.addEventListener('hide.bs.collapse', () => {
+      if (parent) {
+        parent.querySelector('.far.fa-folder-open').className =
+          'far fa-folder fa-fw';
+        parent.querySelector('.fas.fa-angle-down').classList.add('rotate');
+        parent.classList.remove('hide-border-bottom');
+      }
+    });
+
+    // expand sub-categories
+    elem.addEventListener('show.bs.collapse', () => {
+      if (parent) {
+        parent.querySelector('.far.fa-folder').className =
+          'far fa-folder-open fa-fw';
+        parent.querySelector('.fas.fa-angle-down').classList.remove('rotate');
+        parent.classList.add('hide-border-bottom');
+      }
+    });
+  });
+}