Le 14 févr. 2014 à 23:40, C. Scott Ananian <ecmascript at cscott.net> a écrit :

> On Fri, Feb 14, 2014 at 11:50 AM, André Bargull <andre.bargull at udo.edu> wrote:
>> I think Scott is requesting this change:
>> https://gist.github.com/anba/6c75c34c72d4ffaa8de7
> 
> Yes, although my proposed diff (in the linked bug) was the shorter,
> "12. If end is undefined, let relativeEnd be ToInteger(lenVal); else
> let
> relativeEnd be ToInteger(end)."  Same effect, though.
> 

Just a last note. Beyond the philosophical aspect whether arraylikes of negative length make any sense at all, there is a strong technical issue you have probably overlooked: For array methods in general, and for the optional argument of `Array.prototype.copyWithin` in particular (see step 14 of the algorithm), a negative index is not understood as an absolute position, but rather as a position relative to the end of the array. For instance, for an array (or arraylike) of length `n`, if `-3` is passed, it indicates position `n-3`. In your case, it is certainly not the semantics you want. (In fact, everything will happily coerce to `0` at the end of the journey, but it's just happenstance.)

—Claude

Le 14 févr. 2014 à 23:40, C. Scott Ananian <ecmascript at cscott.net> a écrit :

> Yes, although my proposed diff (in the linked bug) was the shorter,
> "12. If end is undefined, let relativeEnd be ToInteger(lenVal); else
> let relativeEnd be ToInteger(end)."  Same effect, though.

Just a last note. Beyond the philosophical aspect whether arraylikes of negative length make any sense at all, there is a strong technical issue you have probably overlooked: For array methods in general, and for the optional argument of `Array.prototype.copyWithin` in particular (see step 14 of the algorithm), a negative index is not understood as an absolute position, but rather as a position relative to the end of the array. For instance, for an array (or arraylike) of length `n`, if `-3` is passed, it indicates position `n-3`. In your case, it is certainly not the semantics you want. (In fact, everything will happily coerce to `0` at the end of the journey, but it's just happenstance.)