If you’d like to create just one instance of a Class, you’d better use this singleton pattern:

var singleton = function() {

  /* Private variables */

  var privateVariable;

  /* Private methods */

  function privateFunction(x) {
    // do something here...
  }

  return {

    /* Public variables */

    publicVariable = 15,

    /* Public methods */

    getVariable: function() {
      return privateVariable;
    },

    setVariable: function() {
      privateVariable = 18;
      privateFunction();
    }
  };

}();

The magic of this pattern lies in the instanciation of the singleton:

the main function is called directly due to the ‘()’ at the end.