交差点の信号 statechart https://xstate.js.org/viz/?gist=de3e4d2adbb2eb0c063a548f1d740f00

machine.js

  // Available variables:
  // - Machine
  // - interpret
  // - assign
  // - send
  // - sendParent
  // - spawn
  // - raise
  // - actions
  // - XState (all XState exports)
  
  const lightMachine = Machine({
    id: 'light',
    initial: 'green',
    states: {
      green: {
        on: {
          timer: 'yello'
        }
      },
      yello: {
        on: {
          timer: 'red',
        }
      },
      red: {
        on: {
          timer: 'green'
        }
      },
    }
  });