在 JavaScript 中为数组的多个元素分配相同的值

Question

Is possible to assign same value to multiple elements of array in JavaScript ?

If i have this array:

  var arr= [
   [0,1],
   [0,1],
   [0,1]
  ];

Is possible to assign value 1 to arr[i][0] for all elements having like output:

  [
   [1,1],
   [1,1],
   [1,1],
   [1,1]
  ]

This output without to use for loop ?

Answer 1

There are multiple ways of achieving this without a for loop, however, Array.fill() is probably easiest and modifies the array in place.

arr.fill([1,1])

Other methods like Array.map() and Array.reduce() will return a new array.

Answer 2

您可以使用地图功能

arr = arr.map(x => [1, x[1]])

Answer 3

You can use map for this as well

 var res = [ [0,1], [0,1], [0,1] ].map(([d, ...rest]) => [1, ...rest]) console.log(res)