for-of loops, IteratorClose and the rest of the iterations in the spec

Boris Zbarsky bzbarsky at
Wed Sep 10 14:23:49 PDT 2014

On 9/10/14, 5:12 PM, Domenic Denicola wrote:
> For, I think it would be ideal to use exact for-of if possible, perhaps after an initial discrimination, instead of manually doing all those things to the iterable.

Again, I basically copied Array.from, except for the IsCallable check...

> Perhaps WebIDL is the best place to do that for now.

For what it's worth, things that consume Web IDL and just want to 
snapshot the iterable will be able to do exactly that with sequence types.

If they want to interleave iteration and operation, of course, they'll 
need something else.

> Right. ReturnIfAbrupt always felt to me like an overreaction to the problem of underspecified exception handling behavior. Something like: "Try: (... substeps ...) Catch _e_: ( ... substeps ... )" would be quite nice, at times.

I'd love for us to get there, while aligning the various web specs (ES 
on the one hand and Web IDL and the various W3C/WHATWG specs on the 


More information about the es-discuss mailing list