On Mon, Feb 17, 2014 at 7:08 AM, Claude Pache <claude.pa...@gmail.com> wrote: > 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.)
I have not overlooked it. The fact that negative `end` is significant is exactly the reason why using `ToLength` on it seems wrong. Even thought `end` defaults to `this.length`, it should still be normalized with `ToInteger` since negative values are semantically valid. But as you point out, I don't think there's any actual behavior change, since everything washes out to `0` at the end. It's just a matter of writing a clearer more consistent spec. --scott _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
