web api instance method

IDBIndex: getKey() method

Available in workers

The getKey() method of the IDBIndex interface returns an IDBRequest object, and, in a separate thread, finds either the primary key that corresponds to the given key in this index or the first corresponding primary key, if key is set to an IDBKeyRange.

If a primary key is found, it is set as the result of the request object. Note that this doesn’t return the whole record as get does.

Syntax

getKey()
getKey(key)

Parameters

key Optional
- : A key or IDBKeyRange that identifies a record to be retrieved. If this value is null or missing, the browser will use an unbound key range.

Return value

An IDBRequest object on which subsequent events related to this operation are fired.

If the operation is successful, the value of the request’s result property is the key for the first record matching the given key or key range.

Exceptions

This method may raise a DOMException of one of the following types:

TransactionInactiveError DOMException
- : Thrown if this IDBIndex’s transaction is inactive.
DataError DOMException
- : Thrown if the key or key range provided contains an invalid key.
InvalidStateError DOMException
- : Thrown if the IDBIndex has been deleted or removed.

Examples

In the following example we open a transaction and an object store, then get the index lName from a simple contacts database. We then open a basic cursor on the index using openCursor — this works the same as opening a cursor directly on an ObjectStore using openCursor except that the returned records are sorted based on the index, not the primary key.

myIndex.getKey('Bungle') is then used to retrieve the primary key of the record with an lName of Bungle, and the result of that request is logged to the console when its success callback returns.

Finally, we iterate through each record, and insert the data into an HTML table. For a complete working example, see our IndexedDB-examples demo repo (View the example live).

function displayDataByIndex() {
  tableEntry.textContent = "";
  const transaction = db.transaction(["contactsList"], "readonly");
  const objectStore = transaction.objectStore("contactsList");

  const myIndex = objectStore.index("lName");
  const getKeyRequest = myIndex.getKey("Bungle");
  getKeyRequest.onsuccess = () => {
    console.log(getKeyRequest.result);
  };

  myIndex.openCursor().onsuccess = (event) => {
    const cursor = event.target.result;
    if (cursor) {
      const tableRow = document.createElement("tr");
      for (const cell of [
        cursor.value.id,
        cursor.value.lName,
        cursor.value.fName,
        cursor.value.jTitle,
        cursor.value.company,
        cursor.value.eMail,
        cursor.value.phone,
        cursor.value.age,
      ]) {
        const tableCell = document.createElement("td");
        tableCell.textContent = cell;
        tableRow.appendChild(tableCell);
      }
      tableEntry.appendChild(tableRow);

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

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.