On Wed, Apr 13, 2016 at 4:32 PM, Caitlin Potter <[email protected]> wrote:
> My read of section 12.8.3.1 ( > https://tc39.github.io/ecma262/#sec-addition-operator-plus-runtime-semantics-evaluation > ), > is that V8 is getting this right. > > ToPrimitive on `{}` will, by default, return “[object Object]” — We first > call `Object.prototype.valueOf()`, which returns `this` (see 19.1.3.7). > Following this, we call `toString()`, and get “[object Object]”. > > Subsequent steps of the algorithm just concatenate the two strings > together. So it looks like the other vendors are getting this wrong? > I don't think that reading is right. Steps 5 and 6 call ToPrimitive without a PreferredType. For objects without a @@toPrimitive property, that ends up calling OrdinaryToPrimitive(input, "number"), which results in NaN. So step 7 isn't called - instead we end up running steps 8-10.
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
