Self executing function (class) with some exposed public function

class.js

/**
 * If class Petar does not already exist, create a new instance of it
 */
window.Petar = window.Petar || {};

Petar.Music = function() {
  
    var innerContent;
    
    function init() {
        innerContent = '';
    };
  
    return {
        init: init
    }
}();

Petar.Music.init();