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.
Deprecated since Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4)
This feature has been removed from the Web standards. Though some browsers may still support it, it is in the process of being dropped. Do not use it in old or new projects. Pages or Web apps using it may break at any time.
Returns the size of a file in bytes.
var size = instanceOfFile.fileSize
Not part of any specification.