[Delayed Clipboard Rendering] Optional argument for callbacks record in ClipboardItem constructor

[sanketj]

Instead of adding a new constructor to ClipboardItem for the delayed callback records, can we expand the existing constructor to include an optional argument?

Before:
[RaisesException] constructor(record<DOMString, Promise> items);
[RaisesException] constructor(record<DOMString, Promise> items, record<DOMString, ClipboardDelayedCallback> callbacks);

After:
[RaisesException] constructor(record<DOMString, Promise> items, optional record<DOMString, ClipboardDelayedCallback> callbacks);

[snianu]

can we expand the existing constructor to include an optional argument

I think we had tried that before and IIRC we ran into some compiler issues. Basically, the compiler was refusing to accept an optional record of callbacks. Perhaps we should figure that out first before we publish this explainer to public?

[anaskim]

We have explored some options to update the IDL. Our current preferred solution is:

typedef (Blob or DOMString) ClipboardItemValue;
callback ClipboardItemValueCallback = ClipboardItemValue ();
typedef Promise<(ClipboardItemValue or ClipboardItemValueCallback)> ClipboardItemInit;

// ...
constructor(record<DOMString, ClipboardItemInit> items);