Attempts to delete the named database. If the database already exists and there are open connections that don't close in response to a versionchange event, the request will be blocked until all they close. If the request is successful request's result will be null.
Attempts to open a connection to the named database with the current version, or 1 if it does not already exist. If the request is successful request's result will be the connection.
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version: number
In the following code snippet, we make a request to open a database, and include handlers for the success and error cases. For a full working example, see our To-do Notifications app (view example live.)
MDN Reference