Allow empty ClipboardItem.

[snianu]

Closes #179

For normative changes, the following tasks have been completed:

• Modified Web platform tests (link to pull request)

Implementation commitment:

• WebKit (https://bugs.webkit.org/show_bug.cgi?id=)
• Chromium (https://bugs.chromium.org/p/chromium/issues/detail?id=1500440)
• Gecko (https://bugzilla.mozilla.org/show_bug.cgi?id=)

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Preview | Diff

[snianu]

@evanstade Please let me know if you have any concern with this change, thanks!

[sanketj]

What is the behavior on other browsers? Are they compliant with the spec after this update?

[snianu]

@EdgarChen @whsieh

[snianu]

I'm not sure if this change is actually required as the existing algorithm in read() already handles the empty clipboard state. We do want to prevent write() method from writing empty ClipboardItems as it is not clear what the result should be in those scenarios - do we clear the clipboard or write supported formats with empty data or do nothing? I'm going to abandon this change but please let me know if I'm missing anything.

[snianu]

Abandoning this PR as per the resolution in the EditingWG meeting.
[17:25] next up: #198
[17:26] trying to speak
[17:26] can you hear me?
[17:26] snianu: audio issues, let's move on for now
[17:26] snianu: nvm audio issues fixed!
[17:27] snianu: if clipboard item is empty and developer writes to clipboard, the write will throw an exception in Chrome but FF/WebKit allows that
[17:28] s/clipboard item is empty/clipboard item list is empty/
[17:28] snianu: creates confusion for web dev since it's unclear if they need to retry, or…
[17:28] q+
[17:29] q+
[17:29] s/developer writes to clipboard/developer reads from clipboard/
[17:29] q-
[17:29] snianu: read should not throw exception, write should throw exception
[17:30] snianu: with current DT APIs dev cannot clear clipboard by writing
[17:30] snianu: with async clipboard API you can write empty item (?)
[17:30] snianu: maybe flag to indicate that clipboard item is intentionally "empty"
[17:30] q+
[17:32] whsieh: if we want to expose a "clear clipboard" API, it should probably be navigator.clipboard.clear() or something
[17:33] johanneswilm: seems we're all in agreement
[17:33] sanketj_: to summarize, allow read empty items