IDBKeyRange - Web APIs

IDBKeyRange - Web APIs | MDN

Instance properties

IDBKeyRange.lower Read only: Lower bound of the key range.
IDBKeyRange.upper Read only: Upper bound of the key range.
IDBKeyRange.lowerOpen Read only: Returns false if the lower-bound value is included in the key range.
IDBKeyRange.upperOpen Read only: Returns false if the upper-bound value is included in the key range.

Static methods

IDBKeyRange.bound(): Creates a new key range with upper and lower bounds.
IDBKeyRange.only(): Creates a new key range containing a single value.
IDBKeyRange.lowerBound(): Creates a new key range with only a lower bound.
IDBKeyRange.upperBound(): Creates a new upper-bound key range.

Instance methods

IDBKeyRange.includes(): Returns a boolean indicating whether a specified key is inside the key range.

The following example illustrates how you'd use a key range. Here we declare a keyRangeValue as a range between values of "A" and "F". 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. This means that the cursor will only retrieve records with keys inside that range. This range includes the values "A" and "F", as we haven't declared that they should be open bounds. If we used IDBKeyRange.bound("A", "F", true, true);, then the range would not include "A" and "F", only the values between them.

function displayData() {
  const keyRangeValue = IDBKeyRange.bound("A", "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.");
    }
  };
}