Final iterator spec

David Bruant bruant.d at
Mon Mar 3 01:35:42 PST 2014

Le 03/03/2014 10:11, Andy Wingo a écrit :
> On Sun 02 Mar 2014 04:18, Domenic Denicola <domenic at> writes:
>> You can just do `if (Symbol.iterator in potentialIterable)`.
> Of course, this can introduce time-of-check-to-time-of-use bugs.
> Actually calling @@iterator on the iterable is more reliable.
This only shifts the problem one step without really solving it. Calling 
@@iterator may return a non-iterator or may return something that looks 
like a iterator ('next' method), but throws when calling 'next'.
I wonder if time-of-check-to-time-of-use bugs can be fully avoided 
entirely in JS?
It might be possible to guarantee some properties in TypeScript assuming 
all consummers of a piece of code are checked by the TypeScript compiler.

In practice, it looks like JS devs have lived well with solution like 
Domenic's one.


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