gistfile1.js

function Car() {
    this.beep = function() {
        alert('beep');
    };
}

function Factory() {
    this.createCar = function(properties) {
        Car.apply(properties);
        return properties;
    };
}

var factory = new Factory();

var car = factory.createCar({
    color: "red"
});

alert(car.color);
car.beep();​