Controllers in your application control the logic of your skill, they respond to alexa alexaEvents, external resources, manipulate the input and give proper responses using your Model, Views and Variables.

States come in one of two ways, they can be an object of mappings from intent name to state.

skill.onState('entry', {
  LaunchIntent: 'launch',
  'AMAZON.HelpIntent': 'help',

Or they can be a function that gets a alexaEvent object.

skill.onState('launch', (alexaEvent) => {
  return { reply: 'LaunchIntent.OpenResponse', to: 'die' };

Your state should respond with a transition. The transition is a plain object that can take directives, to and reply keys.

The entry controller

The entry controller is special in that it’s the default state to go to at the beginning of your session and if your state returns no response.

For example in the next snipped there’s a waiting state that expects an AMAZON.NextIntent or an AMAZON.PreviousIntent, in the case the users says something unexpected like an AMAZON.HelpIntent the state returns undefined, the State Machine framework handles this situations by redirecting to the entry state

skill.onState('waiting', (alexaEvent) => {
  if ( === 'AMAZON.NextIntent') {
    alexaEvent.model.index += 1;
    return { reply: 'Ingredients.Describe', to: 'waiting' }
  } else if ( === 'AMAZON.PreviousIntent') {
    alexaEvent.model.index -= 1;
    return { reply: 'Ingredients.Describe', to: 'waiting' }

The onIntent helper

For the simple pattern of having a controller respond to an specific intent the framework provides the onIntent helper

skill.onIntent('LaunchIntent', (alexaEvent) => {
  return { reply: 'LaunchIntent.OpenResponse', to: 'die' };

If you receive a Display.ElementSelected type request, you could use the same approach for intents and state. Voxa receives this type of request and turns it into DisplayElementSelected Intent

skill.onIntent('DisplayElementSelected', (alexaEvent) => {
  return { reply: 'DisplayElementSelected.OpenResponse', to: 'die' };

Under the hood this creates a new key in the entry controller and a new state