The newVersion read-only property of the IDBVersionChangeEvent interface returns the new version number of the database.

A number that is a 64-bit integer or null if the database is being deleted.

In the following code snippet, we make a request to open a database, and include handlers for the success and error cases. These events are fired via the custom IDBVersionChangeEvent interface. For a full working example, see our To-do Notifications app (view example live).

const note = document.querySelector("ul");

// Let us open version 4 of our database
const DBOpenRequest = window.indexedDB.open("toDoList", 4);

// these two event handlers act on the database being opened
DBOpenRequest.onerror = (event) => {
  note.innerHTML += "<li>Error loading database.</li>";
};

DBOpenRequest.onsuccess = (event) => {
  note.innerHTML += "<li>Database initialized.</li>";

  // store the result of opening the database in the db variable.
  // This is used a lot later on, for opening transactions and suchlike.
  const db = DBOpenRequest.result;
};

• 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).