Add clear history and next item functions.

source/item/item.ts

@@ -31,6 +31,13 @@ export type SerializedItem = {
 /** The key prefix for {@link Item}s. */
 export type ItemKeyPrefix = "item-" | "history-";
 
+/**
+ * Returns the dedicated WebExtension storage area for a given
+ * {@link ItemKeyPrefix}.
+ *
+ * @param prefix The target {@link ItemKeyPrefix}.
+ * @returns The WebExtension storage area.
+ */
 export function storageForPrefix(
   prefix: ItemKeyPrefix,
 ): browser.Storage.StorageArea {
@@ -192,3 +199,42 @@ export async function setBadgeText(): Promise<void> {
     action.setBadgeTextColor({color: "#f2efff"});
   }
 }
+
+/**
+ * Remove all historical items from local WebExtension storage.
+ */
+export async function clearHistory(): Promise<void> {
+  const historyPrefix: ItemKeyPrefix = "history-";
+  const historyItemKeys = await getItemKeys(historyPrefix);
+  const storage = storageForPrefix(historyPrefix);
+  await storage.remove(historyItemKeys);
+}
+
+/**
+ * Opens the next queued item if one is available, otherwise opens the
+ * WebExtension options page.
+ *
+ * @param newTab Open the next item in a new tab (default `false`).
+ */
+export async function openNextItemOrOptionsPage(newTab = false): Promise<void> {
+  const item = await nextItem();
+  if (item === undefined) {
+    await browser.runtime.openOptionsPage();
+    return;
+  }
+
+  const url = item.value.url;
+  await (newTab
+    ? browser.tabs.create({active: true, url})
+    : browser.tabs.update({url}));
+
+  await item.remove();
+  await setBadgeText();
+
+  const historyItem = await createItem(
+    item.value.text,
+    item.value.url,
+    "history-",
+  );
+  await historyItem.save();
+}