Clipboard API example iframe - permission policy error

[RyanFarrah67]

MDN URL

https://developer.mozilla.org/en-US/docs/Web/API/Clipboard/read

What specific section or headline is this issue about?

https://developer.mozilla.org/en-US/docs/Web/API/Clipboard/read#examples

What information was incorrect, unhelpful, or incomplete?

The examples set in the Clipboard API don't work, when copying an image as indicated in the doc to paste it, nothing happens, only errors are thrown.

These demos are presented through an Iframe which causes permission policy issues.

What did you expect to see?

The examples are to work correctly when copying and pasting the image and no errors are to be thrown.

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

OS

Linux Ubuntu 22.04

Browsers

Google Chrome

127.0.6533.72

The error appears in the DevTools console and the iframe.

Firefox

130.0

The error appears directly in the Iframe itself Error: Clipboard read operation is not allowed.

MDN metadata

Page report details

• Folder: en-us/web/api/clipboard/read
• MDN URL: https://developer.mozilla.org/en-US/docs/Web/API/Clipboard/read
• GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/web/api/clipboard/read/index.md
• Last commit: c7edf27
• Document last modified: 2024-07-26T02:57:09.000Z

[RyanFarrah67]

I didn't see it as it is not present in all examples but there is a note about Chromium browsers :

This may not work on chromium browsers as the sample frame is not granted the Permissions-Policy clipboard-read and clipboard-write permissions (required by Chromium browsers).

However, I let this issue open as the problem is also in Firefox.

[hamishwillee]

Are you sure? This is what I see on Firefox

Permission-Policies are supposed to first be set by the server and then that subset can be granted if also set on the frame. Firefox doesn't care about the server so we are able to set the permissions just on the frame.

[RyanFarrah67]

This is what I get :

Strangely, the first left click on the second box does nothing, I need to click a second time for the error to appear.

[hamishwillee]

Can you please try pressing Play and seeing what happens if you run it using the playground?

[RyanFarrah67]

The same, I don't see any error in the console.

[hamishwillee]

Thanks @OnkarRuikar !