IDBObjectStore: openKeyCursor() method

{{ APIRef("IndexedDB") }}

The openKeyCursor() method of the {{domxref("IDBObjectStore")}} interface returns an {{domxref("IDBRequest")}} object whose result will be set to an {{domxref("IDBCursor")}} that can be used to iterate through matching results. Used for iterating through the keys of an object store with a cursor.

To determine if the add operation has completed successfully, listen for the results's success event.

Syntax

openKeyCursor()
openKeyCursor(query)
openKeyCursor(query, direction)

Parameters

• query {{optional_inline}}
  • : The key range to be queried. If a single valid key is passed, this will default to a range containing only that key. If nothing is passed, this will default to a key range that selects all the records in this object store.
• direction {{optional_inline}}
  • : A string telling the cursor which direction to travel. The default is next. Valid values are:
    • next
      • : The cursor is opened at the start of the store; then, the cursor returns all records, even duplicates, in the increasing order of keys.
    • nextunique
      • : The cursor is opened at the start of the store; then, the cursor returns all records, that are not duplicates, in the increasing order of keys.
    • prev
      • : The cursor is opened at the end of the store; then, the cursor returns all records, even duplicates, in the decreasing order of keys.
    • prevunique
      • : The cursor is opened at the end of the store; then, the cursor returns all records, that are not duplicates, in the decreasing order of keys.

Return value

An {{domxref("IDBRequest")}} object on which subsequent events related to this operation are fired.

If the operation is successful, the value of the request's {{domxref("IDBRequest.result", "result")}} property is:

• an {{domxref("IDBCursor")}} object pointing at the first record matching the given query
• null if no matching records were found.

Exceptions

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

• InvalidStateError {{domxref("DOMException")}}
  • : Thrown if this {{domxref("IDBObjectStore")}} or {{domxref("IDBIndex")}} has been deleted.
• TransactionInactiveError {{domxref("DOMException")}}
  • : Thrown if this {{domxref("IDBObjectStore")}}'s transaction is inactive.
• DataError {{domxref("DOMException")}}
  • : Thrown if the specified key or key range is invalid.

Examples

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:

const transaction = db.transaction("name", "readonly");
const objectStore = transaction.objectStore("name");
const request = objectStore.openKeyCursor();
request.onsuccess = (event) => {
  const cursor = event.target.result;
  if (cursor) {
    // cursor.key contains the key of the current record being iterated through
    // note that there is no cursor.value, unlike for openCursor
    // this is where you'd do something with the result
    cursor.continue();
  } else {
    // no more results
  }
};

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).