Async Clipboard API: Allow empty ClipboardItem during read

Category: Miscellaneous
Type: Chromium catches up
Status: In development (Chrome In development)
Intent stage: None

Breaking change: No
Enterprise impact: None
Spec maturity: Working draft
Web Platform Tests: No

WPT details: Currently emptying the clipboard is not exposed to the web, so it's not possible to add a WPT test for it. However we have added browser tests in Chromium: https://chromium-review.googlesource.com/c/chromium/src/+/5010104

Summary

When the system clipboard is either empty or has unsupported formats, paste event returns an empty DataTransfer object, but the promise for `navigator.clipboard.read()`API is rejected. This creates interop differences and confusion among web developers as they aren’t sure why read failed. Currently in Chrome, we throw a DataError. The proposal here is to return an empty ClipboardItem when the system clipboard is either empty or there aren’t any supported formats.

Motivation

When the system clipboard is either empty or has unsupported formats, paste event returns an empty DataTransfer object, but the promise for `navigator.clipboard.read()`API is rejected. This creates interop differences and confusion among web developers as they aren’t sure why read failed. Explainer: https://docs.google.com/document/d/1OLVOESy3zecxY_6jMKdKVxeIGS2Q6mDmzc85rUNrRIE/edit?usp=sharing

Standards & signals

Specification: https://w3c.github.io/clipboard-apis/#dom-clipboard-read
Firefox: Positive
Safari: Shipped/Shipping
Web developers: Positive — This was a feedback from our partners at Office who are migrating from DataTransfer API to Async Clipboard API.
Tracking bug: https://bugs.chromium.org/p/chromium/issues/detail?id=1500440

Ecosystem

Web Platform Tests: https://wpt.fyi/results/?q=async-clipboard-api-allow-empty-clipboarditem-during-read
Chrome Platform Showcase: https://chrome-platform-showcase.paulkinlan-ea.deno.net/features
GenDN reference: https://gendn.paulkinlan-ea.deno.net/features
chrome.dev demos search: https://www.google.com/search?q=site%3Achrome.dev+Async%20Clipboard%20API%3A%20Allow%20empty%20ClipboardItem%20during%20read
MDN Web Docs: https://developer.mozilla.org/en-US/search?q=Async%20Clipboard%20API%3A%20Allow%20empty%20ClipboardItem%20during%20read
Baseline status: https://webstatus.dev/?q=Async%20Clipboard%20API%3A%20Allow%20empty%20ClipboardItem%20during%20read

Docs: https://github.com/w3c/clipboard-apis/issues/179 https://docs.google.com/document/d/1OLVOESy3zecxY_6jMKdKVxeIGS2Q6mDmzc85rUNrRIE/edit?usp=sharing

Samples: https://flash-lateral-nylon.glitch.me/

View on chromestatus.com