FileHandle.onabort
Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
Summary
Specifies an event listener to receive abort events. These events occur when the associated locked file has been aborted with the LockedFile.abort() method.
Syntax
instanceOfFileHandle.onabort = funcRef;
Where funcRef is a function to be called when the abort event occurs.
Specifications
This feature is not part of any current specification. It is no longer on track to become a standard.