basic_fsm.js

function Fsm(states) {
  var self = this;
  function onTransition(state, data) {
    self.state = state;
    self.data = data;
    states[state](data, onTransition);
  }
  onTransition(Object.getOwnPropertyNames(states)[0], null);
}

var fsm = new Fsm({
  'first' : function(data, callback) { callback('second', 2) },
  'second' : function(data, callback) { callback('print', data + 3) },
  'print' : function(data, callback) { console.log(data); },
})