clone.js

// JS (ES6)

obj = { uno: 1, dos: 2 }
var obj2 = Object.assign({}, obj);
obj.tres = 3

// JS (ES5)

obj = { uno: 1, dos: 2 }
var clone = function(original) {
	var copy = Object.create({});
	Object.getOwnPropertyNames(original).forEach(function(name) {
		Object.defineProperty(copy, name, Object.getOwnPropertyDescriptor(original, name));
	});
	return copy;
};
obj2 = clone(obj)
obj.tres = 3