Refactor <ActionsModal> to TypeScript (#34559)

app/javascript/mastodon/models/dropdown_menu.ts

@@ -22,3 +22,29 @@ export type MenuItem =
   | LinkMenuItem
   | ExternalLinkMenuItem
   | null;
+
+export const isMenuItem = (item: unknown): item is MenuItem => {
+  if (item === null) {
+    return true;
+  }
+
+  return typeof item === 'object' && 'text' in item;
+};
+
+export const isActionItem = (item: unknown): item is ActionMenuItem => {
+  if (!item || !isMenuItem(item)) {
+    return false;
+  }
+
+  return 'action' in item;
+};
+
+export const isExternalLinkItem = (
+  item: unknown,
+): item is ExternalLinkMenuItem => {
+  if (!item || !isMenuItem(item)) {
+    return false;
+  }
+
+  return 'href' in item;
+};