IDBCursor: direction property

A string indicating the direction in which the cursor is traversing the data. Possible values are:

next

This direction causes the cursor to be opened at the start of the source.

nextunique

This direction causes the cursor to be opened at the start of the source. For every key with duplicate values, only the first record is yielded.

prev

This direction causes the cursor to be opened at the end of the source.

prevunique

This direction causes the cursor to be opened at the end of the source. For every key with duplicate values, only the first record is yielded.

In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through all the records in the object store. Within each iteration we log the direction of the cursor, something like this:

prev

The cursor does not require us to select the data based on a key; we can just grab all of it. Also note that in each iteration of the loop, you can grab data from the current record under the cursor object using cursor.value.foo. For a complete working example, see our IDBCursor example (View the example live).

function backwards() {
  list.textContent = "";
  const transaction = db.transaction(["rushAlbumList"], "readonly");
  const objectStore = transaction.objectStore("rushAlbumList");

  objectStore.openCursor(null, "prev").onsuccess = (event) => {
    const cursor = event.target.result;
    if (cursor) {
      const listItem = document.createElement("li");
      listItem.textContent = `${cursor.value.albumTitle}, ${cursor.value.year}`;
      list.appendChild(listItem);

      console.log(cursor.direction);
      cursor.continue();
    } else {
      console.log("Entries displayed backwards.");
    }
  };
}

• Using IndexedDB
• Starting transactions: IDBDatabase
• Using transactions: IDBTransaction
• Setting a range of keys: IDBKeyRange
• Retrieving and making changes to your data: IDBObjectStore
• Using cursors: IDBCursor
• Reference example: To-do Notifications (View the example live).