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.
lockedFile property represents the
LockedFile object from which the request was started.
var lockedFile = instanceOfFileRequest.lockedFile
|FileSystem API||Editor's Draft||Draft proposal.|