Generated by XState Viz: https://xstate.js.org/viz

machine.js

const pedestrianStates = {
  initial: 'walk',
  states: {
    walk: {
      after: {
        1000: {
          target: 'wait',
          cond: 'pedestrians'
        }
      },
    },
    wait: {
      after: {
        500: 'stop'
      },
    },
    stop: {
      entry: assign({pedActivated: (context, event) => false})
    }
  }
};

const lightMachine = Machine(
  {
    id: 'pedestrianLight',
    initial: 'green',
    context: {
      pedActivated: false
    },
    states: {
      green: {
        on: {
          TIMER: 'yellow',
          ACTIVATE_PED: {
            target: 'green',
            actions: assign({pedActivated: (context, event) => true})
          }
        },
        after: {
          2000: 'yellow'
        }
      },
      yellow: {
        on: {
          TIMER: 'red',
          ACTIVATE_PED: {
            target: 'yellow',
            actions: assign({pedActivated: (context, event) => true})
          }
        },
        after: {
          2000: 'red'
        }
      },
      red: {
        on: {
          TIMER: 'green',
          ACTIVATE_PED: {
            target: 'red',
            actions: assign({pedActivated: (context, event) => true})
          }
        },
        after: {
          2000: {
            target: 'green',
            cond: 'noPedestrians'
          }
        },
        ...pedestrianStates
      }
    },
  },
  {
    guards: {
      noPedestrians: context => context.pedActivated === false,
      pedestrians: context => context.pedActivated === true
    }
  }
);