Pure JavaScript - Private and public methods

Have you been creating your own classes in pure JavaScript? What if you neeed a private method? How to create them?

var MyClass = (function() {
        function MyClass() {

        var prvMethod = function() {

        MyClass.prototype = {
            init: function() {
                console.log('init ');



        return MyClass;

var mc = new MyClass();

So finally you can access init() but cannot access prvMethod(). It has only access into MyClass() function scope.