Remove dead code and reorganize slightly

src/scripts/modules/expanders.ts

@@ -0,0 +1,53 @@
+function anchorToId(anchor: HTMLAnchorElement) {
+    return anchor.href.replace("./", "");
+}
+
+const stored = localStorage.getItem("expanded") ?? "[]";
+let parsed: string[];
+try {
+    parsed = JSON.parse(stored) as string[];
+}
+catch (e) {
+    parsed = [];
+}
+const state = new Set(parsed);
+const submenus = Array.from(document.querySelectorAll("#menu .submenu-item"));
+for (const sub of submenus) {
+    try {
+        if (state.has(anchorToId(sub.children[0] as HTMLAnchorElement))) sub.classList.add("expanded");
+    }
+    catch (e) {
+        // TODO: create logger
+        console.warn("Could not restore expanded state"); // eslint-disable-line no-console
+        console.error(e); // eslint-disable-line no-console
+    }
+}
+
+export default function setupExpanders() {
+    const expanders = Array.from(document.querySelectorAll("#menu .collapse-button"));
+    for (const ex of expanders) {
+        ex.addEventListener("click", e => {
+            e.preventDefault();
+            e.stopPropagation();
+            // ex.parentElement.parentElement.classList.toggle("expanded");
+            ex.closest(".submenu-item")?.classList.toggle("expanded");
+            const id = anchorToId(ex.closest("a")!);
+            if (state.has(id)) state.delete(id);
+            else state.add(id);
+            localStorage.setItem("expanded", JSON.stringify([...state]));
+        });
+    }
+
+    // In case a linked article lead to a new tree
+    const activeLink = document.querySelector("#menu a.active");
+    if (activeLink) {
+        let parent = activeLink.parentElement;
+        const mainMenu = document.getElementById("#menu");
+        while (parent && parent !== mainMenu) {
+            if (parent.matches(".submenu-item") && !parent.classList.contains("expanded")) {
+                parent.classList.add("expanded");
+            }
+            parent = parent.parentElement;
+        }
+    }
+}