primitive boxing in instanceof due to Symbol.hasInstance

Kevin Smith zenparsing at
Mon Jun 15 17:20:27 UTC 2015

> calls GetMethod on C without checking if it is an Object, this means `1
> instanceof Foo` could be affected by mutating
> `Number.prototype[Symbol.hasInstance]`.

I assume you mean "without checking if O is an object"

> I am assuming this is unintended?

IIUC the point of @@hasInstance is to allow the programmer to define
completely arbitrary semantics for "instanceof" when applied to "C", even
if C is a built-in.  Do you see a problem with this behavior?
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