[英]Object.prototype.isPrototypeOf vs. obj.prototype.isPrototypeOf
I am not looking forward the differences between one and the other. 我不期待彼此之间的差异。 Airbnb already does a great job explaining about it on the style guides repository . Airbnb已经在样式指南存储库中对此做出了出色的解释。
Considering a trivial class and its implementation like the following: 考虑一个琐碎的类及其实现,如下所示:
class C1 {}
const c1Imp = new C1();
Where .prototype
should be inherited from Object . 其中.prototype
应该从Object继承。
Why isn't the following equivalent? 为什么以下等效项不成立?
console.info(Object.prototype.isPrototypeOf.call(C1, c1Imp)); // false
console.info(C1.prototype.isPrototypeOf(c1Imp)); // true
(() => { class C1 {} const c1Imp = new C1(); console.info(c1Imp.constructor.name); console.info(`${Object.prototype.isPrototypeOf.call(C1, c1Imp)} (should be true)`); console.info(`${C1.prototype.isPrototypeOf(c1Imp)} (should be true)`); class C2 {} const c2Imp = new C2(); console.info(c2Imp.constructor.name); console.info(`${Object.prototype.isPrototypeOf.call(C1, c2Imp)} (should be false)`); console.info(`${C1.prototype.isPrototypeOf(c2Imp)} (should be false)`); })();
PS: the question title isn't very clear, feel free to edit as appropriate. PS:问题标题不是很清楚,请随时进行适当的编辑。
You should do this instead: 您应该这样做:
Object.prototype.isPrototypeOf.call(C1.prototype, c1Imp) // true
In your first example, you were calling the Object.prototype.isPrototypeOf
method on C1
itself, while in the second example, you were calling isProtoTypeOf
on the C1.prototype
. 在第一个示例中,您在C1
本身上调用Object.prototype.isPrototypeOf
方法,而在第二个示例中,您在isProtoTypeOf
上调用C1.prototype
。 It's just some tricky semantics. 这只是一些棘手的语义。
The fix as I showed above is to called Object.prototype.isPrototypeOf
on the C1.prototype
itself. 此修复程序正如我上面显示是名为Object.prototype.isPrototypeOf
在C1.prototype
本身。
Check out the updated snippet: 查看更新的代码段:
(() => { class C1 {} const c1Imp = new C1(); console.info(c1Imp.constructor.name); console.info(`${Object.prototype.isPrototypeOf.call(C1.prototype, c1Imp)} (should be true)`); console.info(`${C1.prototype.isPrototypeOf(c1Imp)} (should be true)`); class C2 {} const c2Imp = new C2(); console.info(c2Imp.constructor.name); console.info(`${Object.prototype.isPrototypeOf.call(C1, c2Imp)} (should be false)`); console.info(`${C1.prototype.isPrototypeOf(c2Imp)} (should be false)`); })();
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