Theindex() method of theIDBObjectStoreinterface opens a named index in the current object store, after which it can be usedto, 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

AnIDBIndex object for accessing the index.

Exceptions

InvalidStateErrorDOMException

Thrown if the source object store has been deleted, or the transaction for the object store has finished.

NotFoundErrorDOMException

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 indexlName from a simple contacts database. We then open a basic cursor on theindex usingIDBIndex.openCursor — this works the same as opening a cursordirectly on anObjectStore usingIDBObjectStore.openCursorexcept 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 acomplete working example, see ourIDBIndex 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

Browser compatibility

See also

• 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).