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ronag
approved these changes
Oct 11, 2024
KhafraDev
approved these changes
Oct 11, 2024
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I think this may have use in node core as well. I noticed when working on #3708 that |
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Unfortunately, when examined, there is no difference in the real world, but it is always faster than the original isPrototypeOf. import { bench, run } from "mitata";
const FunctionPrototypeSymbolHasInstance = Function.call.bind(
Function.prototype[Symbol.hasInstance]
);
function A() {
if (!(this instanceof A)) {
return new A();
}
return this;
}
function B() {
if (!(this instanceof B)) {
return new B();
}
return this;
}
class State {
_now = -1;
now() {
return (this._now = (this._now + 1) & 0x7fffffff);
}
}
const array = [];
for (let i = 0; i < 0xff; ++i) {
array.push(Math.random() > 0.5 ? new A() : new B());
}
const state = new State();
const isPrototypeOf = Object.prototype.isPrototypeOf;
const APrototype = A.prototype;
bench("a", () => array[state.now() & 0xff] instanceof A);
bench("b", () =>
FunctionPrototypeSymbolHasInstance(A, array[state.now() & 0xff])
);
bench("c", () => isPrototypeOf.call(A.prototype, array[state.now() & 0xff]));
bench("d", () => isPrototypeOf.call(APrototype, array[state.now() & 0xff]));
await run(); |
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/Symbol.hasInstance#reverting_to_default_instanceof_behavior
benchmark avg (min … max) p75 p99 (min … top 1%) -------------------------------------- ------------------------------- webidl.is.FormData (ok) 7.17 ns/iter 6.91 ns █▄ (6.20 ns … 150.63 ns) 14.65 ns ▁██▃▁▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁ webidl.is.FormData (b.. 8.81 ns/iter 9.03 ns █ (7.62 ns … 101.73 ns) 18.87 ns █▄▁▄▁▁▁▂▁▁▁▁▁▁▁▁▁▁▁▁▁ instanceof (ok) 22.41 ns/iter 23.14 ns █ (19.60 ns … 63.67 ns) 43.04 ns ▁█▂▁▄▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁ instanceof (bad) 23.51 ns/iter 22.61 ns █ (20.53 ns … 122.12 ns) 47.97 ns ▁█▂▃▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁ ┌ ┐ webidl.is.FormData (ok) ┤■ 7.17 ns webidl.is.FormData (b.. ┤■■■■ 8.81 ns instanceof (ok) ┤■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■ 22.41 ns instanceof (bad) ┤■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■ 23.51 ns └ ┘