IDBCursor: advance() method

{{APIRef("IndexedDB")}} {{AvailableInWorkers}}

The advance() method of the {{domxref("IDBCursor")}} interface sets the number of times a cursor should move its position forward.

Syntax

advance(count)

Parameters

• count
  • : The number of times to move the cursor forward.

Return value

None ({{jsxref("undefined")}}).

Exceptions

This method may raise a {{domxref("DOMException")}} of one of the following types:

• TransactionInactiveError {{domxref("DOMException")}}
  • : Thrown if this IDBCursor's transaction is inactive.
• {{jsxref("TypeError")}}
  • : Thrown if the value passed into the count parameter was zero or a negative number.
• InvalidStateError {{domxref("DOMException")}}
  • : Thrown if the cursor is currently being iterated or has iterated past its end.

Examples

In this simple fragment we create a transaction, retrieve an object store, then use a cursor to iterate through the records in the object store. Here we use cursor.advance(2) to jump 2 places forward each time, meaning that only every other result will be displayed. advance() works in a similar way to {{domxref("IDBCursor.continue")}}, except that it allows you to jump multiple records at a time, not just always go onto the next record.

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

  objectStore.openCursor().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);
      cursor.advance(2);
    } else {
      console.log("Every other entry displayed.");
    }
  };
}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

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