Clone/copy

Use ES5 to clone/copy objects

by Stefano

HTML

<a href="https://stackoverflow.com/questions/122102/what-is-the-most-efficient-way-to-clone-an-object">An answer to a SO question</a>

JavaScript

var c = { p:1, 
  e: "what", 
  b: {
    f: function(x) {
      console.log(x);
    }
	}
}
var c2 = Object.assign({}, c);
c2.e = "how";
console.log("c = ", c);
console.log("c2 = ", c2);
// c.b.f = 'c';

c2.b.f('ciao');

console.log(c.prototype === c2.prototype);

if (!Object.assign) {
  Object.defineProperty(Object, 'assign', {
    enumerable: false,
    configurable: true,
    writable: true,
    value: function(target) {
      'use strict';
      if (target === undefined || target === null) {
        throw new TypeError('Cannot convert first argument to object');
      }

      var to = Object(target);
      for (var i = 1; i < arguments.length; i++) {
        var nextSource = arguments[i];
        if (nextSource === undefined || nextSource === null) {
          continue;
        }
        nextSource = Object(nextSource);

        var keysArray = Object.keys(nextSource);
        for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
          var nextKey = keysArray[nextIndex];
          var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
          if (desc !== undefined && desc.enumerable) {
            to[nextKey] = nextSource[nextKey];
          }
        }
      }
      return to;
    }
  });
}