[b] [b = a，0]如何在a和b之间交换？ [英] How does [b][b = a,0] swap between a and b?

问题描述

gdoron 指出，

var a = "a";
var b = "b";

a = [b][b = a,0];

交换 a 和 b ，虽然看起来有点 hacky ，但它引起了我的好奇心，我对它的运作方式非常好奇。这对我没有任何意义。

Will swap a and b, and although it looks a bit of hacky, it has triggered my curiosity and I am very curious at how it works. It doesn't make any sense to me.

推荐答案

var a = "a";
var b = "b";

a = [b][b = a, 0];

让我们将最后一行分成几部分：

Let's break the last line into pieces:

[b]       // Puts b in an array - a safe place for the swap.
[b = a]   // Assign a in b
[b = a,0] // Assign a in b and return the later expression - 0 with the comma operator.

所以最后它是 a = [b] [0] - 分配给 [b] array => b 中的第一个对象> a

so finally it is a =[b][0] - the first object in the [b] array => b assigned to a

现场演示

阅读@am不是我在这个问题上的评论：

逗号运算符何时有用？

这是他的代码......

read @am not I am comments in this question:
When is the comma operator useful?
It's his code...

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