var F = function () {};
var myObj = new F();

console.log(myObj);

getMutableCopy : function (object) {
    var f = function () {};
    f.prototype = object;
    return new f();
}

> function foo {}
> foo.name
  "foo"
> foo.name = "bar"
  "bar"
> foo.name
  "foo"    // <-- looks like it is read only

function copy(parent, name){
  name = typeof name==='undefined'?'Foobar':name;
  var f = eval('function '+name+'(){};'+name);
  f.prototype = parent;
  return new f();
}

var parent = {a:50};
var child = copy(parent, 'MyName');
console.log(child); // Shows 'MyName' in Chrome console.

function Cache(fallback){
  var cache = {};

  this.get = function(id){
    if (!cache.hasOwnProperty(id)){
      cache[id] = fallback.apply(null, Array.prototype.slice.call(arguments, 1));
    }
    return cache[id];
  }
}

var copy = (function(){
  var cache = new Cache(createPrototypedFunction);

  function createPrototypedFunction(parent, name){
    var f = eval('function '+name+'(){};'+name);
    f.prototype = parent;
    return f;
  }

  return function(parent, name){
    return new (cache.get(name, parent, typeof name==='undefined'?'Foobar':name));
  };
})();

my_class = function () {}
my_class.prototype.toString = function () { return 'Name of Class'; }

a = new my_class()
a.does_not_exist()

/**
 * JavaScript Rename Function
 * @author Nate Ferrero
 * @license Public Domain
 * @date Apr 5th, 2014
 */
var renameFunction = function (name, fn) {
    return (new Function("return function (call) { return function " + name +
        " () { return call(this, arguments) }; };")())(Function.apply.bind(fn));
};

/**
 * Test Code
 */
var cls = renameFunction('Book', function (title) {
    this.title = title;
});

new cls('One Flew to Kill a Mockingbird');

Book {title: "One Flew to Kill a Mockingbird"}

var name ="bar";
window["foo"+name] = "bam!";
foobar; // "bam!"

function getmc (object, name) {

    window[name] = function () {};
    window[name].prototype = object;
    return new window[name]();

}

foo = function(){};
foobar = getmc(foo, "bar");
foobar; // ▶ window
foobar.name; // foo
x = new bar; x.name; // foo .. not even nija'ing the parameter works