async-statemachine-example.js

// I have a couple of transition states, "authenticated", "authenticating", "unauthenticated"
const machine = new Machine({
  initial: 'unauthenticated',
  states: {
    unauthenticated: 'authenticating',
    authenticating: ['authenticated', 'unauthenticated'],
    authenticated: 'unauthenticated'
  }
})

// I have a couple of state values (context) related to these
// two states
const auth = {
  state: machine,
  user: null,
  error: null
}

// I have logic transitioing my machine safely, though
// the logic related to it can basically do whatever it wants
// unrelated to the machine
async function login() {
  if (auth.state.machine.transition('authenticating')) {
    try {
      const user = await fetch('/user')      
      if (auth.state.machine.transition('authenticated')) {
        auth.user = user 
      }
    } catch (error) {
      if (auth.state.machine.transition('authenticated')) {
        auth.error = error 
      }
    }
  }
}