Simple State Machine.js

import * as states from './enumMatchStates'
/**
 * Simple State machine in charge of updating the
 * current match state.
 * This state machine is used to drive the UI
 */

 const transitions = {
     START:'start',
     NEXT_MOVE:'nextMove',
     FINISH: 'finish'
 }

/**
 * Function that returns a new state machine
 * with the game transition rules
 */
 function createMachine(initialState=states.CAPTURE_PLAYERS_INFO) {

     return new StateMachine(initialState, {
        [states.CAPTURE_PLAYERS_INFO]: {
            [transitions.START]: states.WAITING_MOVE
        },
        [states.WAITING_MOVE]: {
            [transitions.NEXT_MOVE]: states.WAITING_MOVE,
            [transitions.FINISH]: states.FINISHED
        },
        [states.FINISHED]: {
            [transitions.START]: states.CAPTURE_PLAYERS_INFO
        }
     })
 }

/**
 * Simple state machine, transitions from one state to another using emit(transitionName)
 * I started using the library nanostate, but it doesn't build properly with create-react-app
 * so had to hack this
 */
class StateMachine {
    constructor(initialState, transitions) {
        this.emit = this.emit.bind(this);
        this.state = initialState;
        this.transitions = transitions;
    }
    emit(transition) {
        const stateTransitions = this.transitions[this.state];
        if(stateTransitions && stateTransitions[transition]) {
            this.state = stateTransitions[transition];
            return this.state
        }
        else {
            throw new Error('Invalid transition');
        }
    }
}

 export {createMachine, transitions}