Can you please also file this at https://github.com/whatwg/html/issues ?

(In reply to Simon Pieters from comment #1)
> Can you please also file this at https://github.com/whatwg/html/issues ?

Happy to do it: 
https://github.com/whatwg/html/issues/217

Note: just to be clear, there are other additions to HTMLInputElement that haven't been properly accounted for in this bug.

partial interface HTMLInputElement {
                attribute boolean directory;
    readonly    attribute boolean isFilesAndDirectoriesSupported;
    Promise<sequence<(File or Directory)>> getFilesAndDirectories();
    void                                   chooseDirectory();
};

(In reply to Arun from comment #0)
> In order to enable Directory Upload via the HTMLInputElement, Mozilla and
> Microsoft propose a change: the addition of the getFilesAndDirectories()
> method, initially proposed in the WICG.
[...]
> These provide asynchronous ways of navigating user-selected files and
> directories. This bug is to specify getFilesAndDirectories on the
> HTMLInputElement.

I'm supportive of this proposal, of course, but the goal of the incubator group is to make sure that proposals are feasible and have reasonably broad support before being adopted by working groups.

Do you think the criteria such as those proposed in the "Intent to migrate" template [1] have been reached, for example?

[1] https://wicg.github.io/admin/intent-to-migrate.html

(In reply to Adrian Bateman [MSFT] from comment #4)
> (In reply to Arun from comment #0)
> > In order to enable Directory Upload via the HTMLInputElement, Mozilla and
> > Microsoft propose a change: the addition of the getFilesAndDirectories()
> > method, initially proposed in the WICG.
> [...]
> > These provide asynchronous ways of navigating user-selected files and
> > directories. This bug is to specify getFilesAndDirectories on the
> > HTMLInputElement.
> 
> I'm supportive of this proposal, of course, but the goal of the incubator
> group is to make sure that proposals are feasible and have reasonably broad
> support before being adopted by working groups.
> 
> Do you think the criteria such as those proposed in the "Intent to migrate"
> template [1] have been reached, for example?
> 
> [1] https://wicg.github.io/admin/intent-to-migrate.html

Adrian:

My concern is that the discussions taking place at WICG currently are tapering off, and in general, appear to be favoring a migration towards the WG (WHATWG for the HTML bits, and WebApps for the File API bits). It seems to me that technical discussions might be more robust there, but I'd like you to weigh in on that matter also.

Mozilla's plans include an implementation of the feature. 

Would formally filling out the intent to migrate doc help move things over? Can I encourage you to contribute some of your metrics, at least based on the Chrome-emulation that you announced you would do on the listserv? That appears give us "first guess" metrics for usage according to the Data clause of the "intent to migrate" template. Also, I'm happy to work on the "intent to migrate" portion of things, if that helps move things over.

HTML5.1 Bugzilla Bug Triage: Incubation needed

This bug constitutes a request for a new feature of HTML. The current guidelines [1], rather than track such requests as bugs or issues, please create a proposal outlining the desired behavior, or at least a sketch of what is wanted (much of which is probably contained in this bug), and start the discussion/proposal in the WICG [2]. As your idea gains interest and momentum, it may be brought back into HTML through the Intent to Migrate process [3].
[1] https://github.com/w3c/html#contributing-to-this-repository
[2] https://www.w3.org/community/wicg/
[3] https://wicg.github.io/admin/intent-to-migrate.html