javascript - 以功能方式交换两个数组元素

Question

我正在尝试在 javascript (es6) 中以函数式方式交换数组中的 2 个元素

let arr = [1,2,3,4,5,6]
let result = swap(arr, 1, 2) // input: array, first element, second element
// result=[1,3,2,4,5,6]

我能想到的唯一方法是:

const swap = (arr, a, b) => 
            arr.map( (curr,i) => i === a ? arr[b] : curr )
               .map( (curr,i) => i === b ? arr[a] : curr )

但是这段代码在数组上运行了两次，而且根本不可读。对漂亮干净的功能代码有什么建议吗？

谢谢。

Answer 1

简短可靠但不可否认难以阅读:

const swap = (x, y) => ([...xs]) => xs.length > 1
 ? ([xs[x], xs[y]] = [xs[y], xs[x]], xs)
 : xs;

const xs = [1,2,3,4,5];

const swap12 = swap(1, 2);

console.log(
  swap12(xs),
  "exception (one element):",
  swap12([1]),
  "exception (empty list):",
  swap12([])
);