为什么在JavaScript中[5,6,8,7][1,2]= 8 ?

I can't wrap my mind around this quirk.

我想不起来这个怪癖。

[1,2,3,4,5,6][1,2,3]; // 4
[1,2,3,4,5,6][1,2]; // 3

I know [1,2,3] + [1,2] = "1,2,31,2", but I can't find what type or operation is being performed.

我知道[1、2、3]+[1、2]= "1、2、31、2"，但我找不到正在执行的类型或操作。

4 个解决方案

#1

372

[1,2,3,4,5,6][1,2,3];
      ^         ^
      |         |
    array       + — array subscript access operation,
                    where index is `1,2,3`,
                    which is an expression that evaluates to `3`.

The second [...] cannot be an array, so it’s an array subscript operation. And the contents of a subscript operation are not a delimited list of operands, but a single expression.

第二个[…不能是数组，所以它是数组下标操作。下标操作的内容不是限定操作数的列表，而是一个表达式。

Read more about the comma operator here.

在这里阅读更多有关逗号运算符的信息。

4 个解决方案

#1

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