Object.prototype.hasOwnProperty.call和{} .hasOwnProperty.call之间的区别。 [英] Difference between Object.prototype.hasOwnProperty.call and {}.hasOwnProperty.call.(eslint rule guard-for-in)

问题描述

在eslint规则后卫保护中，使用<$直接在中使用c $ c>是不正确的。好的做法是

In the eslint rule guard-for-in , use for in directly is incorrect. The good practice is

for (key in foo) {
    if (Object.prototype.hasOwnProperty.call(foo, key)) {
        doSomething(key);
    }
    if ({}.hasOwnProperty.call(foo, key)) {
        doSomething(key);
    }
}

我的问题是何时 Object .prototype.hasOwnProperty.call（foo，key）和 {}。hasOwnProperty.call（foo，key）会导致不同的结果吗？任何人都可以举一个具体的例子吗？

My question is when Object.prototype.hasOwnProperty.call(foo, key) and {}.hasOwnProperty.call(foo, key) will lead different result? Anyone can show a specific example?

推荐答案

它们永远不会 ¹ 导致不同的结果，因此将两者都考虑在内正确。

They'll never¹ lead to different results, which is why both of them are considered correct.

对象 {} 始终从对象原型继承而没有自己的键，因此访问 .hasOwnProperty 方法将为您提供所需的东西。并且 Object.prototype 是全局 Object 构造函数的不可写属性，因此它始终引用对象原型

The object {} always inherits from the object prototype and has no own keys, so accessing the .hasOwnProperty method on it will get you what you want. And Object.prototype is a non-writable property of the global Object constructor, so it always refers to the object prototype as well.

现在，在某些情况下，表达式不能执行您想要的操作：

Now, there are some cases where the expression does not do what you wanted it to do:

• 有人确实覆盖了全局 Object 变量


• 有人确实掩盖了您对象中的对象标识符，以使其不引用全局


• 有人确实覆盖了 Object.prototype.hasOwnProperty 和其他东西


• 有人确实用其他东西覆盖了 Function.prototype.call

• Someone did overwrite the global Object variable
• Someone did shadow the Object identifier in your scope so that it doesn't refer to the global
• Someone did overwrite Object.prototype.hasOwnProperty with something else
• Someone did overwrite Function.prototype.call with something else

_{1：显然，前两种情况只与 Object.prototype 引用混淆，但是他们仍然很前卫，不容忽视。}

_{1: Obviously, the first two edge cases only mess with the Object.prototype reference, but they're still edgy enough to be ignored.}

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