Thanks, Array and Function (as well as RegExp) actually directly specify that calling them with and without new produces equivalent results where `Object` doesn't and actually has a hole (in what it _may_ do to host objects).
It's just baffling that `Object` is defined so differently. I wonder if there are old browsers that differ on this, or there is a bigger reason for this behaviour. On Sat, Jun 13, 2015 at 12:05 AM, Andrea Giammarchi < andrea.giammar...@gmail.com> wrote: > I think historically `Array`, `Function`, and `Object` can be used with or > without `new` and the result is exactly the same ... since, about, ever. > > Agreed if that's actually indeed the case, we could have just one > definition for those 3 constructors (not just Object) > > Regards > > On Fri, Jun 12, 2015 at 10:19 PM, Benjamin Gruenaum <benjami...@gmail.com> > wrote: > >> Ok, so I gave this a few hours in the open. >> >> So, I'm looking at the ES5 specification (also checked the current ES >> draft which is similar) at the definition of what new Object and Object do. >> To my surprise: >> >> - `new Object` describes a whole algorithm of how the object constructor >> works - treating what happens with different kinds of values. Basically >> calls `ToObject` on non objects - identity on objects and builds on null >> and undefined. >> - `Object` has a special first step for null and undefined where it >> builds an object and then calls `ToObject` on primitives and identity on >> objects. >> >> After reading the description a few times - they seem identical. However, >> clearly from the spec they do *something* different. For example in Array - >> calling new Array is specified as the function call Array(…) is equivalent >> to the object creation expression new Array(…) with the same arguments.` >> >> The only difference I've been able to identify with the help of a friend >> is that the behaviour can be different on host objects. Where `Object` must >> return the same host object and `new Object` _may_ return the same host >> object. >> >> I've taken a look at the ES3 specification and it too uses the same >> definition so I suspect this is something that has been there for a long >> time. >> >> - Why are `Object` and `new Object` specified differently? >> - If there is no actual reason, can the definition be simplified for the >> next version of the spec? (I think simplifying the spec is important and >> possibly underrated) >> >> Sorry if I'm missing something obvious. >> >> Originally asked on Stack Overflow - >> http://stackoverflow.com/q/30801497/1348195 >> >> _______________________________________________ >> es-discuss mailing list >> es-discuss@mozilla.org >> https://mail.mozilla.org/listinfo/es-discuss >> >> >
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