function runPage() {

  var a;

  a = applyConstruct(Array, [1, "two", 3, "four"]);

  display("a instanceof Array? " + (a instanceof Array));

  display("a.join(',') = " + a.join(','));

​

  function applyConstruct(ctor, params) {

    var obj, newobj;

    function fakeCtor() {

    }

    fakeCtor.prototype = ctor.prototype;

    obj = new fakeCtor();

    obj.constructor = ctor;

    newobj = ctor.apply(obj, params);

    if (newobj !== null && (typeof newobj === "object" || typeof newobj === "function")) {

        obj = newobj;

    }

    return obj;

  }

  function display(msg) {

    var p = document.createElement('p');

    p.innerHTML = msg;

    document.body.appendChild(p);

  }

}