The lowerOpen read-only property of the IDBKeyRange interface returns a boolean indicating whether the lower-bound value is included in the key range.

A boolean value:

The following example illustrates how you'd use a key range. Here we declare keyRangeValue = IDBKeyRange.upperBound("F", "W", true, true); — a range that includes everything between "F" and "W" but not including them — since both the upper and lower bounds have been declared as open (true). We open a transaction (using IDBTransaction) and an object store, and open a Cursor with IDBObjectStore.openCursor, declaring keyRangeValue as its optional key range value.

After declaring the key range, we log its lowerOpen property value to the console, which should appear as "true": the lower bound is open, so won't be included in the range.

function displayData() {
  const keyRangeValue = IDBKeyRange.bound("F", "W", true, true);
  console.log(keyRangeValue.lowerOpen);

  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.");
    }
  };
}

• 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).