In this implementation, the state machine takes an object states that defines the possible states and actions for each input. Each state is a nested object with keys representing the inputs that can trigger a transition to another state. The value of each input key is the name of the destination state, or null if the input should be ignored. The…

stateMachineTransitionActions.js

class StateMachine {
  constructor(states) {
    this.states = states;
    this.currentState = null;
  }
  
  transition(input) {
    const nextState = this.states[this.currentState][input];
    if (nextState) {
      this.currentState = nextState;
      this.states[this.currentState].action();
    }
  }
  
  run(inputs) {
    for (const input of inputs) {
      this.transition(input);
    }
  }
}

const states = {
  A: {
    a: 'B',
    b: 'C',
    action: () => console.log('State A')
  },
  B: {
    b: 'A',
    c: 'C',
    action: () => console.log('State B')
  },
  C: {
    a: 'A',
    action: () => console.log('State C')
  }
};

const machine = new StateMachine(states);
machine.currentState = 'A';
machine.run(['a', 'b', 'c', 'a', 'b']);