Copy arbitrary n-dimensional array in JavaScript?

Question

Basically I am looking for a copy of a generic function (array) that will return an identical n-dimensional array without any reference to the previous one.

Answer 1

This works for arrays, it will not work for nested objects (these are not arrays):

function copy(arr){
    var new_arr = arr.slice(0);
    for(var i = new_arr.length; i--;)
        if(new_arr[i] instanceof Array)
            new_arr[i] = copy(new_arr[i]);
    return new_arr;
}

Use it as follows:

var arr = [
   [[1,2,3],[75]], 100,
   [[[1]]], [],
   [1,[2,[3],4],5], 6, 7, 8
];

var new_arr = copy(arr);

Answer 2

Using jQuery (works for arrays and "simple" objects):

var a = [[1,[2,3]],[4]];
var b = $.extend(true, [], a);
a[0][0] = 42;             // modify object in a
alert(JSON.stringify(b)); // [[1,[2,3]],[4]]

Or JSON direct (if all objects are JSON-izable):

var a = [[1,[2,3]],[4]];
var b = JSON.parse(JSON.stringify(a))
a[0][0] = 42;             // modify object in a
alert(JSON.stringify(b)); // [[1,[2,3]],[4]]

In older versions of IE (8? 7?), Padding for the JSON object will be required.

Answer 3

Paulpro. , , , (new_arr [i]) (arr [i]) new_arr.length arr.length.

function copy(arr){
var new_arr = arr.slice(0);
for(var i = arr.length; i--;)
    if(new_arr[i] instanceof Array)
        new_arr[i] = copy(arr[i]);
return new_arr;
}

, (new_arr [i]) , , .slice , arr [i], .

, Paulpro , , -, , . , , ?

function copy(arr){
if(arr[0] instanceof Array){
    var new_arr = new Array(arr.length);
    for(var i = arr.length; i--;)
        new_arr[i] = copy(arr[i]);
}
else{var new_arr = arr.slice(0);}
return new_arr;
}

Answer 4

; Array.prototype.clone(), N .

Array.prototype.clone = function(){
  return this.reduce((p,c,i) => (p[i] = Array.isArray(c) ? c.clone() : c, p),[])
}

function arrayND(...n){
  return n.reduceRight((p,c) => c = (new Array(c)).fill(true).map(e => Array.isArray(p) ? p.clone() : p ));
}

var arr = arrayND(...[4,4,4],8); //last argument is the initializing value
arr[0][1][3] = "eight";
console.log(JSON.stringify(arr));

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