Create an empty two dimensional array in Javascript, with keys

Question

I'm trying to create a matrix in Javascript, but one which has predefined keys for the X and Y axis.

For example I have the following keys

const x = [2,4,6,8]
const y = [10,20,40,60,80]

I found the following snippet which creates an empty two dimensional array with 4 rows and 5 columns

[...Array(4)].map(x=>Array(5).fill(0))       

I'm wondering if it's possible to create these arrays (objects), but using provided keys to go with it.

So the end result would look like this.

{
    2 => {10 => 0, 20 => 0, 40 => 0, 60 => 0, 80 => 0}
    4 => {10 => 0, 20 => 0, 40 => 0, 60 => 0, 80 => 0}
    6 => {10 => 0, 20 => 0, 40 => 0, 60 => 0, 80 => 0}
    8 => {10 => 0, 20 => 0, 40 => 0, 60 => 0, 80 => 0}
}

Answer 1

您可以通过循环和减少数据来创建所需的对象。

的回调Array#reduce将累加器作为第一个参数，这里是一个对象，将迭代数组的值作为第二个参数。

作为在startValue的reduce，它需要一个（种空）对象，并usdes这个对象添加属性。为了使该对象（即累加器）为下一个循环（和最终结果）做好准备，必须将其返回。

var x = [2, 4, 6, 8],
    y = [10, 20, 40, 60, 80],
    result = x.reduce((r, k) => {
        r[k] = y.reduce((q, l) => {
            q[l] = 0;
            return q;
        }, {});
        return r;
    }, {});

console.log(result);