Setting prototype and performance issues

Asked Oct 27 '17 at 07:06

Active Oct 27 '17 at 07:06

Viewed 26 times

There is a big red warning label on the Mozilla page for Object.setPrototypeOf and I've been trying to understand what exactly the optimization issues with changing the prototype are, but I don't think I have, so I'll come right out and ask: Will the code below cause performance problems or is it safe?

class A {}

function B () {
    if ( !new.target ) {
        return new B();
    }
}

B.prototype = A.prototype;
B.prototype.constructor = B;

A little background: Function B is supposed to be the only part of the library that will be exposed. Ideally it should be possible to use B without new but also use instanceof B to identify objects.

asked Oct 27 '17 at 07:06

1

Changing the prototype of an existing instance is "the slow operation". – Teemu Oct 27 '17 at 07:11
Oh! So I completely misunderstood that then? – Oct 27 '17 at 07:12
1

@PeterCoester Yes. Nowhere in your code are you using `Object.setPrototypeOf` :-) – Bergi Oct 27 '17 at 07:18
Thanks Teemu! Thanks Bergi! And sorry for posting a duplicate! – Oct 27 '17 at 07:19

Setting prototype and performance issues

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