web api instance method

IDBObjectStore: index() method

Available in workers

The index() method of the IDBObjectStore interface opens a named index in the current object store, after which it can be used to, for example, return a series of records sorted by that index using a cursor.

Syntax

index(name)

Parameters

name
- : The name of the index to open.

Return value

An IDBIndex object for accessing the index.

Exceptions

InvalidStateError DOMException
- : Thrown if the source object store has been deleted, or the transaction for the object store has finished.
NotFoundError DOMException
- : Thrown if there is no index with the given name (case-sensitive) in the database.

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.

Finally, we iterate through each record, and insert the data into an HTML table. For a complete working example, see our IDBIndex example in 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");
  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.