todo.js

import Vue from 'vue';
import Vuex from 'vuex';
import axios from 'axios';

Vue.use(Vuex);

const state = {
  count: 0,
  todos: [],
};

const mutations = {
  setTodos: (state, payload) => state.todos = payload,
  addItem: (state, payload) => state.todos.push({ title: payload, completed: false }),
  finishItem: (state, payload) => state.todos[payload].completed = !state.todos[payload].completed,
};

const actions = {
  fetchTodos({ commit }) {
    const endpoint = 'https://jsonplaceholder.typicode.com/todos';
    const response = res => commit('setTodos', res.data.slice(0, 5));
    const error = e => console.log(e);

    axios
      .get(endpoint)
      .then(response)
      .catch(error);
  },
};

export default {
  state,
  mutations,
  actions,
};