Le 25 févr. 2014 à 01:54, Allen Wirfs-Brock <allen at wirfs-brock.com> a écrit :

> 
> On Feb 24, 2014, at 4:18 PM, Claude Pache wrote:
> 
>> 
>> Personally, I consider that the impossibility to "yield a hole" must be considered as a feature, not a bug. Holes are useful in order to have consistent results for `Array.from([1, , 3])` (i.e., getting an exact copy), but their use should not be encouraged. (Note that, if you really want to, you can always (painfully) wrap a generator producing sentinel values with a hand-made iterable that forwards the results, transforming sentinel values into holes in the process.)
> 
> It easy enough to write an keys or entries iterator that ignores holes:
> 
> function *sparseKeys(array) {
>   for (indx of array.keys()) if (Object.hasOwnProperty(array, key)) yield indx;
> }
> 
> function *sparseEntries(array) {
>   for (entry of array.entries()) if (Object.hasOwnProperty(array, entry[0])) yield entry;
> }
> 
> The same thing could be done for values but that seems less useful.
> 
> Allen


Indeed, but the question was about producing/forwarding holes rather than skip them, so that, e.g., `Array.from` could replace the elements at the correct positions.

—Claude

Indeed, but the question was about producing/forwarding holes rather than skip them, so that, e.g., `Array.from` could replace the elements at the correct positions.