Clone Multidimensional Array in javascript

Question

I want to make a clone of multidimensional Array so that i can play arround with the clone array without affecting main Array.

I\'m using following function to do so

Answer 1

You need to use recursion

var a = [1,2,[3,4,[5,6]]];

Array.prototype.clone = function() {
    var arr = [];
    for( var i = 0; i < this.length; i++ ) {
//      if( this[i].constructor == this.constructor ) {
        if( this[i].clone ) {
            //recursion
            arr[i] = this[i].clone();
            break;
        }
        arr[i] = this[i];
    }
    return arr;
}

var b = a.clone()

console.log(a);
console.log(b);

b[2][0] = 'a';

console.log(a);
console.log(b);

/*
[1, 2, [3, 4, [5, 6]]]
[1, 2, [3, 4, [5, 6]]]
[1, 2, [3, 4, [5, 6]]]
[1, 2, ["a", 4, [5, 6]]]
*/

Any other objects in the original array will be copied by reference though

Answer 2

I found that this approach is better than meouw's :

var source = [
  [1, 2, {c:1}],
  [3, 4, [5, 'a']]
];

// Create a new method ontop of the "Array" primitive prototype:
Array.prototype.clone = function() {
  function isArr(elm) {
    return String(elm.constructor).match(/array/i) ? true : false;
  }

  function cloner(arr) {
    var arr2 = arr.slice(0),
        len = arr2.length;

    for (var i = 0; i < len; i++)
      if (isArr(arr2[i]))
        arr2[i] = cloner(arr2[i]);

    return arr2;
  }
  return cloner(this);
}

// Clone
var copy = source.clone();

// modify copy
copy[0][0] = 999;

console.dir(source);
console.dir('**************');
console.dir(copy);

Another method, which can only work on data sets which have primitives
as values (String, Numbers, Objects) :

var source = [
  [1,2, {a:1}],
  ["a", "b", ["c", 1]]
];

// clone "srouce" Array
var copy = JSON.parse(JSON.stringify(source));

// modyfy clone
copy[0][0] = 999;

// print both arrays
console.dir(copy)
console.log('***********')
console.dir(source)

Answer 3

vsync is correct, my first answer doesn't handle var a = [[1,2],[3,4]];
So here's an improved version

var a = [[1,2],[3,4]];
Array.prototype.clone = function() {
    var arr = this.slice(0);
    for( var i = 0; i < this.length; i++ ) {
        if( this[i].clone ) {
            //recursion
            arr[i] = this[i].clone();
        }
    }
    return arr;
}

var b = a.clone()

console.log(a);
console.log(b);

b[1][0] = 'a';

console.log(a);
console.log(b);

//[[1, 2], [3, 4]]
//[[1, 2], [3, 4]]
//[[1, 2], [3, 4]]
//[[1, 2], ["a", 4]]