Cancelable promises proposal

Boris Zbarsky bzbarsky at
Thu Aug 27 01:23:06 UTC 2015

On 8/3/15 8:15 PM, Glen Huang wrote:
> Ideally, if the same resolve & reject callback combination is passed more than once, the same promise is always returned

That's a backwards-incompatible change from what browsers are shipping, 

> (I can't think of a use case where promises could stop to work, if promises were specced with this additional rule, but maybe I overlooked)

As long as no one uses the promise as a key in a Map or anything else 
that relies on its object identity...

> Do you have a use case where the same callback will be passed to the same promise more than once?

Not offhand, but I would be shocked if no one is doing it.


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