vue2的todolist入门小项目的详细解析

$ npm install -g vue-cli$ vue init ，比如 vue init webpack todolist$ cd todolist$ npm install$ npm run dev

//后面的为注释讲解， ~表示串联index.html的对应内容import 'todomvc-app-css/index.css'import Vue from 'vue'//添加localStoragevar STORAGE_KEY = 'todos-vuejs-2.0'var todoStorage = { fetch: function () {  var todos = JSON.parse(localStorage.getItem(STORAGE_KEY) || '[]')  todos.forEach(function (todo, index) {   todo.id = index  })  todoStorage.uid = todos.length  return todos }, save: function (todos) {  localStorage.setItem(STORAGE_KEY, JSON.stringify(todos)) }}//用过滤器筛选出三种状态var filters = { all(todos) {  return todos }, active(todos) {  return todos.filter((todo) => {   return !todo.completed  }) }, completed(todos) {  return todos.filter((todo) => {   return todo.completed  }) },}let app = new Vue({ el: '.todoapp',  // ~ <section class="todoapp"> data: {  msg: 'hello world',  title: '待做清单',  // 渲染标题 ~ {{title}}  newTodo: '',   todos: todoStorage.fetch(), // ~ v-show="todos.length" ； ~ {{todos.length>1?'items':'item'}} 渲染 li ~ v-for="(todo,index) in filteredTodos"   editedTodo: '',  // 空的编辑对象  hashName: 'all'   },  watch: {  todos: {   handler: function (todos) {    todoStorage.save(todos)   },   deep: true  } },  computed: {  remain() {   return filters.active(this.todos).length  //未完成事项的数量 ~ {{remain}}  },   isAll: {   // ~ v-model="isAll"   get() {    return this.remain === 0   },   set(value) {    this.todos.forEach((todo) => {     todo.completed = value    })   }  },  filteredTodos() {  //用hashName过滤出当前页面的todos ~ v-for="(todo,index) in filteredTodos"    return filters[this.hashName](this.todos)  } }, methods: {  addTodo(e) { //输入值为空时，不添加（trim去除前后空格） ~ v-model.trim="newTodo"    if (!this.newTodo) {    return   }   this.todos.push({    id: todoStorage.uid++,    content: this.newTodo,    completed: false //结合v-model 根据completed状态绑定样式 ~:class="{completed:todo.completed； ~ v-model="todo.completed"   })   this.newTodo = ''  },  removeTodo(index) {  //绑定x样式，点击删除该todo ~ @click="removeTodo(index)"   this.todos.splice(index, 1)  },  editTodo(todo) {     //编辑 ~ @dblclick="editTodo(todo)"   this.editCache = todo.content //储存编辑前的内容   this.editedTodo = todo // 点击编辑里面的内容而不是只是空文本框~ editing:todo==editedTodo}"  },  doneEdit(todo, index) { //失去焦点后 ~ @blur="doneEdit(todo)"；@keyup.enter="doneEdit(todo)"   this.editedTodo = null //不存在编辑了或者说编辑已完成   if (!todo.content) { //如果编辑后没有内容了，删除该todo    this.removeTodo(index)   }  },  cancelEdit(todo) {  //按esc键取消此次编辑操作 ~ @keyup.esc="cancelEdit(todo)">   this.editedTodo = null      todo.content = this.editCache //当esc取消编辑时，还原编辑前的内容  },  clear() { //点击清除已完成的功能 ~ @click="clear"   this.todos = filters.active(this.todos) //获取并渲染未完成的事项 ~   } }, directives: {  //自定义属性 ~ v-focus="todo == editedTodo"  focus(el, value) { //文本框双击获取焦点   if (value) {    el.focus()   }  } }})//hash（url地址中#以及之后的字符）function hashChange() { // ~ :class="{selected:hashName=='all'}"；:class="{selected:hashName=='active'}"；:class="{selected:hashName=='completed'}" let hashName = location.hash.replace(/#//?/, '') //正则表达式去除#/？，获取如all，active，completed if (filters[hashName]) {  //如果过滤状态的hashName存在  app.hashName = hashName //给整个app变量里的hashName赋上那个值 } else {  location.hash = ''  //取消  app.hashName = 'all' //否则就赋值‘all'，回到全部事项的页面 }}window.addEventListener('hashchange', hashChange) //全局监听hash