put
Adds or updates a record in store with the given value and key.
If the store uses in-line keys and key is specified a "DataError" DOMException will be thrown.
If put() is used, any existing record with the key will be replaced. If add() is used, and if a record with the key already exists the request will fail, with request's error set to a "ConstraintError" DOMException.
If successful, request's result will be the record's key.