JavaScript: Private properties

private.js

/* Constructor */
function Klass(text, separator) {

    this.text = text;
    this.separator = separator;

    this.__bind(); // Set context to private methods
}

Klass.prototype = (function() {

    /* Private properties */
    var _ = {

        privateField: 'World',

        privateMethod: function() {
            return this.separator + _.privateField + Klass.staticMethod() + $.privateStaticMethod();
        }

    };

    /* Private static properties */
    var $ = {

        privateStaticMethod: function() {
            return ' =)';
        }

    };

    /* Public properties */
    var properties = {

        publicMethod: function() {
            return this.text + _.privateMethod();
        }

    };

    /**
     * Set context to private methods
     * @private
     */
    properties.__bind = function() {
        for(var prop in _) if(_.hasOwnProperty(prop) && typeof _[prop] === 'function') {
            _[prop] = _[prop].bind(this);
        }
    };

    return properties;

})();

/* Public static properties */
Klass.staticMethod = function() {
    return '!';
};

console.log(new Klass('Hello', ', ').publicMethod()); // Hello, World! =)
console.log(Klass.staticMethod()); // !