This attribute is not part of the FileAPI spec and it has been marked as deprecated in bug 1048291 the 31st of May 2016.
It's currently used by the 0.01% of the pages: https://telemetry.mozilla.org/new-pipeline/dist.html#!cumulative=0&end_date=2018-04-30&keys=__none__!__none__!__none__&max_channel_version=nightly%252F61&measure=USE_COUNTER2_DEPRECATED_FileLastModifiedDate_PAGE&min_channel_version=null&processType=*&product=Firefox&sanitize=1&sort_keys=submissions&start_date=2018-03-12&table=0&trim=1&use_submission_date=0 Currently only Chrome and Firefox support this attribute. Firefox bug: 1458883. Chrome bug: https://bugs.chromium.org/p/chromium/issues/detail?id=839372 WPT: https://github.com/w3c/web-platform-tests/pull/10821 _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
