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

machine.js

  // Available variables:
  // - Machine
  // - interpret
  // - assign
  // - send
  // - sendParent
  // - spawn
  // - raise
  // - actions
  // - XState (all XState exports)
  
const historyMachine = Machine({
  id: 'history',
  initial: 'idle',
  context: {
    history: ['https://blog.zfanw.com'],
    index: 0,
  },
  states: {
    idle: {
      on: {
        PUSH: {
          target: 'idle',
          actions: assign({
            history: ({ history, index }, { url }) => {
              if (history.length - 1 === index) {
                return [...history, url]
              } else {
                return [...history.slice(0, index + 1), url]
              }
            },
            index: ({ index }, event) => index + 1,
          }),
        },
        FORWARD: {
          target: 'idle',
          actions: assign({
            index: (context, event) => context.index + 1,
          }),
          cond: (context, event) => context.index < context.history.length - 1,
        },
        BACK: {
          target: 'idle',
          actions: assign({
            index: (context, _event) => context.index - 1,
          }),
          cond: (context, event) => context.index > 0,
        },
      },
    },
  },
})