Deep cloning an Object/Array

JavaScript performance comparison

Revision 42 of this test case created by robertsky

Info

There is no quick and easy facility for cloning an object, Some people recommend using JQuery.extend others JSON.parse/stringify

http://stackoverflow.com/questions/122102/what-is-the-most-efficient-way-to-clone-a-javascript-object

If you want the fastest possible clone function. I would personally anticipate the data structure of your object and write a custom clone to handle it.

Preparation code

<script src="//code.jquery.com/jquery-2.1.3.min.js"></script>
 
<script>
Benchmark.prototype.setup = function() {
    var oldObject = {
      a: 1,
      b: {
        c: [33],
        r: 9
      },
      d: 4,
      e: 5,
      f: function() {
        return 6;
      },
      g: [7, 8, [9, 10]],
      h: {
        i: {
          j: {
            k: {
              l: [11, 22]
            }
          }
        }
      }
    };
   
    var oldArray = [1, {
        c: [33],
        r: 9
      },
      4, 5,
      function() {
        return 6;
      },
      [7, 8, [9, 10]], {
        i: {
          j: {
            k: {
              l: [11, 22]
            }
          }
        }
      }
    ];
   
    function clone_recursive(obj) {
      var n = {};
      if (obj instanceof Array) {
        n = [];
      }
   
      function deepCopy(obj, obj1) {
        var i
        for (i in obj) {
          if (obj[i] instanceof Object) {
            if (obj[i] instanceof Array) {
              obj1[i] = [];
            } else {
              obj1[i] = {};
            }
            deepCopy(obj[i], obj1[i]);
          } else {
            obj1[i] = obj[i];
          }
        }
   
        return n;
      }
      deepCopy(obj, n);
      return n;
    }
   
   
    function clone_iterative(object) {
      var result = {};
      if (object instanceof Array) {
        result = [];
      }
      var stack = [result, object];
      var curr, base;
      while (curr = stack.pop()) {
        var base = stack.pop();
        for (var key in curr) {
          var value = curr[key];
          if (typeof value === 'object') {
            if (value instanceof Array) {
              stack.push(base[key] = []);
            } else {
              stack.push(base[key] = {});
            }
   
            stack.push(value)
          } else {
            base[key] = value;
          }
        }
      }
      return result;
    }
};
</script>

Preparation code output

Test runner

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Testing in unknown unknown
Test Ops/sec
jQuery.extend() deep
var newObject = jQuery.extend(true, {}, oldObject);
var newArray = jQuery.extend(true, [], oldArray);
pending…
JSON stringify/parse
var newObject = JSON.parse(JSON.stringify(oldObject));
var newArray = JSON.parse(JSON.stringify(oldArray));
pending…
clone Recursive
var newObject = clone_recursive(oldObject);
var newArray = clone_recursive(oldArray);
pending…
Clone Iterative
var newObject = clone_iterative(oldObject);
var newArray = clone_iterative(oldArray);
pending…

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