Create copy of multi-dimensional array, not reference - JavaScript [duplicate]

Since it sounds like you're dealing with an Array of Arrays to some unknown level of depth, but you only need to deal with them at one level deep at any given time, then it's going to be simple and fast to use .slice().

var newArray = [];for (var i = 0; i < currentArray.length; i++)    newArray[i] = currentArray[i].slice();

Or using .map() instead of the for loop:

var newArray = currentArray.map(function(arr) {    return arr.slice();});

So this iterates the current Array, and builds a new Array of shallow copies of the nested Arrays. Then when you go to the next level of depth, you'd do the same thing.

Of course if there's a mixture of Arrays and other data, you'll want to test what it is before you slice.

I'm not sure how much better JSON.stringify and JSON.parse than encode and decode, but you could try:

JSON.parse(JSON.stringify(array));

Something else I found (although I'd modify it a little):

http://www.xenoveritas.org/blog/xeno/the-correct-way-to-clone-javascript-arrays

function deepCopy(obj) {  if (typeof obj == 'object') {    if (isArray(obj)) {      var l = obj.length;      var r = new Array(l);      for (var i = 0; i < l; i++) {        r[i] = deepCopy(obj[i]);      }      return r;    } else {      var r = {};      r.prototype = obj.prototype;      for (var k in obj) {        r[k] = deepCopy(obj[k]);      }      return r;    }  }  return obj;}

As you asked for performance, I guess you also would go with a non-generic solution. To copy a multi-dimensional array with a known number of levels, you should go with the easiest solution, some nested for-loops. For your two-dimensional array, it simply would look like this:

var len = arr.length,    copy = new Array(len); // boost in Safarifor (var i=0; i<len; ++i)    copy[i] = arr[i].slice(0);

To extend to higher-dimensional arrays, either use recursion or nested for loops!

The native slice method is more efficient than a custom for loop, yet it does not create deep copies, so we can use it only at the lowest level.