1 files changed, 49 insertions, 0 deletions
diff --git a/content/frontend/shared/dom_parse_toc.js b/content/frontend/shared/dom_parse_toc.js
new file mode 100644
index 00000000..552550a1
--- /dev/null
+++ b/content/frontend/shared/dom_parse_toc.js
@@ -0,0 +1,49 @@
+/* eslint-disable import/prefer-default-export */
+import { findChildByTagName } from './dom';
+
+const TAG_LI = 'LI';
+const TAG_A = 'A';
+const TAG_UL = 'UL';
+
+/**
+ * Parses the given HTML Table of Contents into a data structure
+ *
+ * ```
+ * type Item = { text: String, href: String, id: String, items: Item[] }
+ *
+ * parseTOC: Element => Item[]
+ * ```
+ *
+ * @param {Element} menu Parent <ul> element
+ */
+export const parseTOC = menu => {
+  const items = [];
+
+  if (!menu) {
+    return items;
+  }
+
+  menu.childNodes.forEach(li => {
+    if (li.tagName !== TAG_LI) {
+      return;
+    }
+
+    const link = findChildByTagName(li, TAG_A);
+    const subMenu = findChildByTagName(li, TAG_UL);
+
+    if (!link) {
+      return;
+    }
+
+    const item = {
+      text: link.textContent,
+      href: link.getAttribute('href'),
+      id: link.id,
+      items: parseTOC(subMenu),
+    };
+
+    items.push(item);
+  });
+
+  return items;
+};