Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The isAutoLocale read-only property of the IDBIndex interface returns a boolean value indicating whether the index had a locale value of auto specified upon its creation (see createIndex()'s optionalParameters.)


A boolean value.


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 IDBIndex.openCursor — this works the same as opening a cursor directly on an ObjectStore using IDBObjectStore.openCursor except that the returned records are sorted based on the index, not the primary key.

The isAutoLocale value is logged to the console.

function displayDataByIndex() {
  tableEntry.innerHTML = '';
  const transaction = db.transaction(['contactsList'], 'readonly');
  const objectStore = transaction.objectStore('contactsList');

  const myIndex = objectStore.index('lName');

  myIndex.openCursor().onsuccess = (event) => {
    const cursor =;
    if (cursor) {
      const tableRow = document.createElement('tr');
      tableRow.innerHTML = `<td>${}</td>`
                         + `<td>${cursor.value.lName}</td>`
                         + `<td>${cursor.value.fName}</td>`
                         + `<td>${cursor.value.jTitle}</td>`
                         + `<td>${}</td>`
                         + `<td>${cursor.value.eMail}</td>`
                         + `<td>${}</td>`
                         + `<td>${cursor.value.age}</td>`;

    } else {
      console.log('Entries all displayed.');


Not currently part of any specification.

Browser compatibility

BCD tables only load in the browser

See also