function shouldBe(actual, expected) { if (actual !== expected) throw new Error('bad value: ' + actual); } function test(object) { return "hello" in object; } noInline(test); for (var i = 0; i < 1e6; ++i) { shouldBe(test({ hello: 42 }), true); shouldBe(test({ hello: undefined, world: 44 }), true); shouldBe(test({ helloworld: 43, ok: 44 }), false); } function selfCache(object) { return "hello" in object; } noInline(selfCache); var object = {}; object.hello = 42; for (var i = 0; i < 1e6; ++i) shouldBe(selfCache(object), true); object.world = 43; shouldBe(selfCache(object), true); object.world = 43; shouldBe(selfCache({ __proto__: object }), true); delete object.hello; shouldBe(selfCache(object), false); shouldBe(selfCache({ __proto__: object }), false);