Question

我有一个二维数字数组：array1。我想映射到array1内的每个数组，并对每个数组中的数字进行排序，然后将它们返回到新的数组：sortedRows。我知道在数组上进行映射会返回一个新数组，但是当我在映射过程中对每个内部数组进行排序时，它将对array1内的所有数字以及sortedRows进行排序。

我已经尝试过将array1分别映射到行，然后将映射/排序映射到sortedRows，并且我已经尝试使用spread运算符进行复制（行= [... array1]）。两次尝试在下面都得到相同的结果。

let array1 = [[5, 3, 4, 6, 7, 8, 9, 1, 2], 
             [6, 7, 2, 1, 9, 5, 3, 4, 8],
             [1, 9, 8, 3, 4, 2, 5, 6, 7],
             [8, 5, 9, 7, 6, 1, 4, 2, 3],
             [4, 2, 6, 8, 5, 3, 7, 9, 1],
             [7, 1, 3, 9, 2, 4, 8, 5, 6],
             [9, 6, 1, 5, 3, 7, 2, 8, 4],
             [2, 8, 7, 4, 1, 9, 6, 3, 5],
             [3, 4, 5, 2, 8, 6, 1, 7, 9]]

let sortedRows = array1.map(arr => arr.sort((a, b) => a - b))

console.log(array1)
console.log(sortedRows)
// expected

[ [5, 3, 4, 6, 7, 8, 9, 1, 2], 
  [6, 7, 2, 1, 9, 5, 3, 4, 8],
  [1, 9, 8, 3, 4, 2, 5, 6, 7],
  [8, 5, 9, 7, 6, 1, 4, 2, 3],
  [4, 2, 6, 8, 5, 3, 7, 9, 1],
  [7, 1, 3, 9, 2, 4, 8, 5, 6],
  [9, 6, 1, 5, 3, 7, 2, 8, 4],
  [2, 8, 7, 4, 1, 9, 6, 3, 5],
  [3, 4, 5, 2, 8, 6, 1, 7, 9]]
[ [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ] ]


//actual

[ [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ] ]
[ [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ],
  [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ] ]

Answer 1

.sort突变了原始数组，所以当您拥有

array1.map(arr =>

那里的arr指向现有的子数组-如果在其上调用.sort，则将更改该子数组。

请先复制数组的副本：

const sortedRows = array1.map(arr => arr.slice().sort((a, b) => a - b))

let array1 = [[5, 3, 4, 6, 7, 8, 9, 1, 2], 
             [6, 7, 2, 1, 9, 5, 3, 4, 8],
             [1, 9, 8, 3, 4, 2, 5, 6, 7],
             [8, 5, 9, 7, 6, 1, 4, 2, 3],
             [4, 2, 6, 8, 5, 3, 7, 9, 1],
             [7, 1, 3, 9, 2, 4, 8, 5, 6],
             [9, 6, 1, 5, 3, 7, 2, 8, 4],
             [2, 8, 7, 4, 1, 9, 6, 3, 5],
             [3, 4, 5, 2, 8, 6, 1, 7, 9]];

const sortedRows = array1.map(arr => arr.slice().sort((a, b) => a - b));

document.write(array1.join('<br>'));
document.write('<br><br><br>' + sortedRows.join('<br>'));

在.map中排序会影响原始数组，而不是返回新数组

1 个答案: