Note that as of Firefox 40, IndexedDB transactions have relaxed durability guarantees to increase performance (see bug 1112702
.) Previously in a
was fired only when all data was guaranteed to have been flushed to disk. In Firefox 40+ the
event is fired after the OS has been told to write the data but potentially before that data has actually been flushed to disk. The
event may thus be delivered quicker than before, however, there exists a small chance that the entire transaction will be lost if the OS crashes or there is a loss of system power before the data is flushed to disk. Since such catastrophic events are rare most consumers should not need to concern themselves further.