Javascript 数组等于零但不等于本身 [英] Javascript array equal to zero but not itself

问题描述

我一直在 JavaScript 中使用数组，但无法弄清楚为什么会发生这种情况:

I've been playing around with arrays in JavaScript and cannot figure out why this happens:

console.log(0 == 0)
//true

console.log([] == 0)
//true

console.log(0 == [])
//true

console.log([] == [])
//false

console.log([] == ![])
// true

空数组左右都等于0，但为什么不等于自身?

The empty array is equal enough to zero both left and right, but why isn't it equal to itself?

我意识到比较两个对象不会导致 true，但是如果比较，为什么它们会被强制为 0(或错误，不应该是这种情况)将它们与 0 进行比较，而如果将它们与另一个数组进行比较，则会作为对象受到威胁?

I realise that comparing two objects would not result true, but why are they coerced to 0 (or falsy, which shouldn't be the case) if you compare them to 0, while threated as an object if you compare them to the other array?

推荐答案

由于一直没有给出完整的答案，现在我真的明白了，我会自己提供答案.

Since the complete answer is never given and I actually understand it now, I'll provide the answer myself.

我在 Ecma-262 pdf 中找到了这个:

I found this in the Ecma-262 pdf:

它基本上读到 [] == 0 与 Number([]) == 0 相同，后者与 0 == 0 相同 这是真的.这不适用于严格的 ===.

It basically reads that [] == 0 is the same as Number([]) == 0 which is the same as 0 == 0 which is true. This does not apply to strict ===.

除了第一条规则(x 与 y 相同)之外，没有其他规则可以比较对象.这意味着一切都一样，内存地址也是如此.由于它们不共享相同的内存地址，因此适用规则 10(返回 false).

There is no rule to compare objects other then rule number one, which is x is the same as y. This means the same in everything, also memory address. Since they are not sharing the same memory address, rule 10 applies (return false).

比较 x == y，其中 x 和 y 是值，产生真或错误的.这样的比较执行如下:

The comparison x == y, where x and y are values, produces true or false. Such a comparison is performed as follows:

1. 如果Type(x)与Type(y)相同，则

一个.返回执行严格相等比较的结果x === y.

a. Return the result of performing Strict Equality Comparison x === y.

如果 x 为 null 且 y 为 undefined，则返回 true.

If x is null and y is undefined, return true.

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