使用切片，散布和贴图变异的阵列数组

Question

This question has been asked here and more importantly here . I tried all the answers and none solved my issue. It's very basic.

I have the following array. My various attempts at copying do not persist after splicing, or performing any destructive action. Even the copies are mutated. How can I copy this so the original version persists?

var arrs = [ [ 3 ], [ 7, 4 ], [ 2, 4, 6 ], [ 8, 5, 9, 3 ] ]

var arrsCopy1 = arrs.slice()

var arrsCopy2 = arrs.map(arr => {
  return arr
})

var arrsCopy3 = [...arrs]


//test one of the copies
arrsCopy3.forEach(arr => {
  return arr.splice(0, arr.length)
})
arrs, arrsCopy1, arrsCopy2, arrsCopy3 => [[],[],[],[]]

Here is a fiddle that demos my problem (using reverse() instead of splice )

Answer 1

You could do it recursively

const copyArr = (element) => {
    //If the element is a primitive
    if (element !== Object(element)) {
        return element;
    //The element is an array
    } else {
        return element.map(subelement => copyArr(subelement));
    }
}

Answer 2

尝试使用JSON方法：

var arrCopy = JSON.parse(JSON.stringify(arr));

Answer 3

I just found this and it seems to solve the issue.

I was thrown off my the JSON.parse .

var clonedArray = JSON.parse(JSON.stringify(originalArray));