​

(function(){

​

  window.greet = function(firstName, lastName) {

    var _firstName = capitaliseFirstLetter(firstName),

        _lastName = capitaliseFirstLetter(lastName),

        greeting = buildGreeting(_firstName, _lastName);

    console.log(greeting);

  };

​

  function buildGreeting(firstName, lastName) {

    return "Good Morning " + firstName + " " + lastName;

  }

​

  function capitaliseFirstLetter(string) {

    return string.charAt(0).toUpperCase() + string.slice(1);

  }

})();

​

greet('john', 'smith');

​