Opening local file from Webpage/JavaScript

I think you're referring to the feature on dropbox.com that lets a user click an "open" button to open the file on their local computer instead of in the web browser.

There's no API to replicate this. You can imagine why, for security purposes, we don't want other web pages to be able to trigger this behavior.

Yes, I am referring to that feature.

But... The open functionality works only for files in Dropbox folder, so in order to open it one must know its identity.
All the Dropbox file privacy is built up on that identity, so it is not easily guessable according to Dropbox security standards.
Dropbox could also force-show confirmation dialog in case of direct file opening.
Assuming the file opening from dropbox.com webpage is safe, I could not find anything to flag up in quick STRIDE I ran.

May be I missed some aspect, could you please enlighten me here? At least for curiosity.

Thank you.

"All the Dropbox file privacy is built up on that identity, so it is not easily guessable according to Dropbox security standards."

I'm not sure what identity you're referring to. The identity of a file in Dropbox is its path, and these are often easily guessable. Even an app that knows about my files in Dropbox certainly shouldn't be able to open them on my computer without my consent. (Imagine the case of a malicious app that writes a file with malware and then causes my computer to open that file.)

We'll consider this idea (with a confirmation dialog) a feature request, but there are no immediate plans to add it.

With the identity I was referring to a link to the file that people can use to share files, like

https://.../1/view/kh8awq....
Having a possibility to open such links directly on end users computer or even having this option through Chooser API would be excellent.
Thank you for adding this to the wishlist and hope to see the feature soon to implement better integration with Dropbox.
Best regards.

I would really need this kind of functionality. If anything, one could limit it to confirmation dialogues or allow for specific extensions only (excluding .jar, .exe, bash files etc.).

Exactly the same thing needed here.
@Steve M: You said that it will be considered as a feature request. What has become of that? Is there any possibility that it would be implemented any time soon now? We would really need it ASAP.

We're still tracking this as a feature request, but there are no current plans to implement this.