In it, you can create and delete object stores and build and remove indices. onerror = ( event ) => Īs indicated previously, onupgradeneeded is the only place where you can alter the structure of the database. More on this later in Creating or updating the version of the database below, and the IDBFactory.open reference page. If the database does exist but you are specifying an upgraded version number, an onupgradeneeded event is triggered straight away, allowing you to provide an updated schema in its handler. If the database doesn't already exist, it is created by the open operation, then an onupgradeneeded event is triggered and you create the database schema in the handler for this event. The version of the database determines the database schema - the object stores in the database and their structure. The second parameter to the open method is the version of the database. The result for the open function is an instance of an IDBDatabase. Most other asynchronous functions in IndexedDB do the same thing - return an IDBRequest object with the result or error. The call to the open() function returns an IDBOpenDBRequest object with a result (success) or error value that you handle as an event.
The open request doesn't open the database or start the transaction right away. See that? Opening a database is just like any other operation - you have to 'request' it. Js // Let us open our database const request = window.
