IDBKeyRange: lowerBound() static method

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

The lowerBound() static method of the {{domxref("IDBKeyRange")}} interface creates a new key range with only a lower bound. By default, it includes the lower endpoint value and is closed.

Syntax

IDBKeyRange.lowerBound(lower)
IDBKeyRange.lowerBound(lower, open)

Parameters

• lower
  • : Specifies the lower bound of the new key range.
• open {{optional_inline}}
  • : Indicates whether the lower bound excludes the endpoint value. The default is false.

Return value

{{domxref("IDBKeyRange")}}: The newly created key range.

Exceptions

• DataError {{domxref("DOMException")}}
  • : Thrown if the key associated with the lower parameter is not a valid key.

Examples

The following example illustrates how you'd use a lower bound key range. Here we declare keyRangeValue = IDBKeyRange.lowerBound("F", false); — a range that includes the value "F" and everything after it. We open a transaction (using {{domxref("IDBTransaction")}}) and an object store, and open a Cursor with {{domxref("IDBObjectStore.openCursor")}}, declaring keyRangeValue as its optional key range value. This means that the cursor will only retrieve the record with the key value "F" and all that come after it. If we used IDBKeyRange.lowerBound("F", true);, then the range would not include "F"; only the values after it.

[!NOTE] For a more complete example allowing you to experiment with key range, have a look at our IDBKeyRange-example repo (view the example live too.)

function displayData() {
  const keyRangeValue = IDBKeyRange.lowerBound("F");

  const transaction = db.transaction(["fThings"], "readonly");
  const objectStore = transaction.objectStore("fThings");

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

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