A SFC TodoApp with vue2

README.md

how to Run ?

see https://cli.vuejs.org/zh/guide/prototyping.html

# install 
npm install -g @vue/cli-service-global

# run
vue serve TodoApp.vue

helper.js

const STORAGE_KEY = `todo-app-vue2`;
export const todoStorage = {
  fetch() {
    const todos = JSON.parse(localStorage.getItem(STORAGE_KEY) || '[]');
    todos.forEach((todo, index) => {
      todo.id = index;
    });

    todoStorage.uid = todos.length;
    return todos;
  },
  save(todos) {
    localStorage.setItem(STORAGE_KEY, JSON.stringify(todos));
  },
};

// visibility filters
export const filters = {
  all: function (todos) {
    return todos;
  },
  active: function (todos) {
    return todos.filter(function (todo) {
      return !todo.completed;
    });
  },
  completed: function (todos) {
    return todos.filter(function (todo) {
      return todo.completed;
    });
  },
};

TodoApp.vue

<template>
  <div id="app">
    <section class="todoapp">
      <header class="header">
        <h1>Todos</h1>
        <input
          class="new-todo"
          type="text"
          autofocus
          autocomplete="off"
          placeholder="What needs to be done?"
          v-model="newTodo"
          @keyup.enter="addTodo"
        />
      </header>
      <section class="main">
        <input type="checkbox" id="toggle-all" class="toggle-all" v-model="allDone" />
        <label for="toggle-all"></label>
        <ul class="todo-list">
          <li
            class="todo"
            :class="{ completed: todo.completed, editing: todo === editedTodo }"
            v-for="todo in filteredTodos"
            :key="todo.id"
          >
            <div class="view">
              <input type="checkbox" class="toggle" v-model="todo.completed" />
              <label @dblclick="editTodo(todo)">{{ todo.title }}</label>
              <button class="destroy" @click="removeTodo(todo)"></button>
            </div>
            <input
              type="text"
              class="edit"
              v-model="todo.title"
              v-todo-focus="todo === editedTodo"
              @keyup.enter="doneEdit(todo)"
              @keyup.esc="cancelEdit(todo)"
              @blur="doneEdit(todo)"
            />
          </li>
        </ul>
      </section>
      <footer class="footer">
        <span class="todo-count">
          <strong>{{ remaining }}</strong>
          {{ remaining | pluralize }} left
        </span>
        <ul class="filters">
          <li><a href="#/all">All</a></li>
          <li><a href="#/active">Active</a></li>
          <li><a href="#/completed">Completed</a></li>
        </ul>
        <button class="clear-completed" @click="removeCompleted" v-show="todos.length > remaining">Clear completed</button>
      </footer>
    </section>
    <footer class="info">
      <p>Double-click to edit a todo</p>
      <p>Written by <a href="void:javascript(0)">Frank Fan</a></p>
      <p>Part of <a href="http://todomvc.com">TodoMVC</a></p>
    </footer>
  </div>
</template>

<script>
import { todoStorage, filters } from './helper';

export default {
  data() {
    return {
      newTodo: '',
      todos: todoStorage.fetch(),
      editedTodo: null,
      visibility: this.getHash() || 'all',
    };
  },

  watch: {
    todos: {
      handler: function (todos) {
        todoStorage.save(todos);
      },
      deep: true,
    },
  },

  computed: {
    filteredTodos() {
      return filters[this.visibility](this.todos);
    },
    remaining() {
      return filters.active(this.todos).length;
    },
    allDone: {
      get() {
        console.log('get');
        return this.remaining === 0;
      },
      set(value) {
        console.log('set ', value);
        this.todos.forEach(todo => todo.completed = value);
      },
    },
  },

  mounted() {
    window.addEventListener('hashchange', () => {
      const visibility =  this.getHash();
      console.log('hashchange ', visibility);
      if (filters[visibility]) {
        this.visibility = visibility;
      } else {
        window.location.hash = '';
        this.visibility = 'all';
      }
    });
  },

  filters: {
    pluralize(n) {
      return n === 1 ? 'item' : 'items';
    },
  },

  methods: {
    getHash() {
      return location.hash.replace(/#\/?/, '');
    },

    addTodo() {
      const todo = this.newTodo.trim();
      if (!todo) return;
      this.todos.push({
        id: todoStorage.uid++,
        title: todo,
        completed: false,
      });
      this.newTodo = '';
    },
    removeTodo(todo) {
      this.todos.splice(this.todos.indexOf(todo), 1);
    },
    editTodo(todo) {
      this.beforeEditCache = todo.title;
      this.editedTodo = todo;
    },
    doneEdit(todo) {
      if (!this.editedTodo) return;
      this.editedTodo = null;
      todo.title = todo.title.trim();
      if (!todo.title) {
        this.removeTodo(todo);
      }
    },
    cancelEdit(todo) {
      this.editedTodo = null;
      todo.title = this.beforeEditCache;
    },
    removeCompleted() {
      this.todos = filters.active(this.todos);
    },
  },

  directives: {
    'todo-focus': function (el, binding) {
      if (binding.value) {
        el.focus();
      }
    },
  },
};
</script>

<style>
@import 'https://cdn.jsdelivr.net/npm/todomvc-app-css@2.3.0/index.css';
</style>