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

machine.js

const wait = ms => new Promise(r => setTimeout(() => r(), ms));

const fetchPosts = (context, event) => {
  const { q: num } = context;
  console.log('> fetchPosts',num)

  if (num == 5) {
    return new Promise((r, reject) => reject(new Error('Oh too bad...')));
  }

  if (num % 2) {
    return new Promise(resolve => resolve({ id: Math.random(), title: 'foo' }));
  }
  
  return fetch('https://jsonplaceholder.typicode.com/posts/' + num)
    .then(res => res.json())
    .then(data => {
      return data;
    });
};

/* const fetchPosts = async (context, event) => {
  const result = await fetchPostsSrc(context, event);
  console.log({ result });
  await wait(1000);
  return result;
}; */

const fetchMachine = Machine({
  id: 'fetch',
  initial: 'idle',
  context: {
    retries: 0,
    q: 0,
    error: '',
  },
  states: {
    idle: {
      on: {
        FETCH: 'loading',
      },
    },
    loading: {
      invoke: {
        id: 'fetchPosts',
        src: fetchPosts,
        onDone: {
          target: 'success',
          actions: (c, e) => {
            c.q += 1; 
            console.log({ success: e.data });
          },
        },
        onError: {
          target: 'failure',
          actions: (c, e) => {
            console.log({ fail: e.data });
          },
        },
      },
      on: {
        RESOLVE: 'success',
        REJECT: 'failure',
      },
    },
    success: {
      //type: 'final',
      on: {
        RETRY: {
          target: 'loading',
        },
      },
    },
    failure: {
      on: {
        RETRY: {
          target: 'loading',
          actions: assign({
            retries: (context, event) => context.retries + 1,
          }),
        },
      },
    },
  },
});