gistfile1.js

var myObject = function (someParam) {

	var privateMember = "foobar";

	return {
		publicMethod: function () {
			return "Hi! " + someParam + " " + privateMember;
		}
	};
	
};

var foo = new myObject("This is a test!");

console.log(foo.publicMethod()); // "Hi! This is a test! foobar"
console.log(foo.privateMember); // undefined