let HelloWorld = {
  onCommand: function(event) {
    let stringBundle = document.getElementById("helloWorldBundle");
    let hours = new Date().getHours();
    let greeting = (hours < 12) ? stringBundle.getString("morningGreeting")
                                : stringBundle.getString("eveningGreeting");
    let message = stringBundle.getFormattedString("helloWorld", [greeting]);
    dump(message + "\n");
  }
};