3. Vue脚手架

3.1 安装脚手架

切换淘宝镜像

npm config set registry https://registry.npm.taobao.org

安装命令

npm install -g @vue/cli

3.2 render函数

3.3 修改默认设置

3.4 ref属性

1. 被用于给元素或子组件注册引用信息 (id 代替者)

2. 应用在 html 标签上获取的是真实的 DOM 元素，应用在组件标签上是组件实例对象 (vc)

   1. 使用方式:

   打标识：<h1 ref="xxx">...</h1> 或 <School ref="xxx"></School>

   获取：this.$refs.xxx

3.5 props配置

3.6 mixin混入

功能：可以把多个组件共用的配置提取成一个混入对象

使用方式：

1. 定义混合

   {
       data(){...},
       methods:{...},
       ...
   }
   

2. 使用混合

   1. 全局混合：Vue.mixin(xxx)
   2. 局部混合：mixins:['xxx']

3.7 plugins

3.8 scoped样式

作用：让样式在局部生效，防止冲突

写法：<style scoped>

3.9 Todo-list案例

1. 组件化编程流程
   1. 拆分静态组件：组件要按照功能点拆分，命名不要与 html 元素冲突
   2. 实现动态组件：考虑好数据存放位置，数据是一个组件在用，还是一些组件在用：
      1. 一个组件在用：放在组件自身即可
      2. 一些组件在用：放在他们共同的父组件上（状态提升）
   3. 实现交互：从绑定事件开始
2. props适用于：
   1. 父组件 ==> 子组件 通信
   2. 子组件 ==> 父组件 通信（要求父先给子一个函数）
3. 使用 v-model 时要切记：v-model 绑定的值不能是 props 传过来的值，因为 props 是不能够修改的
4. props 传过来的若是对象类型的值，修改对象中的属性时 Vue 不会报错，但不推荐这样做

src/App.vue

<template>
  <div id="root">
    <div class="todo-container">
      <div class="todo-wrap">
        <MyHeader :addTodo="addTodo" />
        <MyList 
          :todos="todos" 
          :changeState="changeState" 
          :deleteTodo="deleteTodo"
        />
        <MyFooter 
          :allCheck="allCheck"  
          :getNum="getNum"
          :getDoneNum="getDoneNum"
          :deleteDone="deleteDone"
         />
    	</div>
    </div>
  </div>
</template>

<script>
  import MyHeader from './components/MyHeader'
  import MyList from './components/MyList'
  import MyFooter from './components/MyFooter.vue'
  import { nanoid } from 'nanoid'

  export default {
    name: 'App',
    components: { MyHeader, MyList, MyFooter },
    data() {
      return {
        todos:[
          {id:'001',title:'抽烟',done:true},
          {id:'002',title:'喝酒',done:false},
          {id:'003',title:'开车',done:true}
        ]
      }
    },
    methods: {
      addTodo(t){
        this.todos.unshift({id:nanoid(), title:t, done:false})
      },
      changeState(id){
        this.todos.forEach((t)=>{
          if (t.id === id) {
            t.done = !t.done
            return
          }
        })
      },
      deleteTodo(id){
        this.todos = this.todos.filter((t)=>{
          return t.id !== id
        })
      },
      allCheck(checked) {
        this.todos.forEach((t)=>{
          t.done = checked
        })
      },
      getNum(){
        return this.todos.length
      },
      getDoneNum(){
        return this.todos.reduce((pre, current)=>pre + (current.done ? 1 : 0), 0)
      },
      deleteDone(){
        this.todos = this.todos.filter((t)=>{
          return !t.done
        })
      }
    }
  }
</script>

<style>
  /*base*/
  body {background: #fff;}
  .btn {display: inline-block;padding: 4px 12px;margin-bottom: 0;font-size: 14px;
    line-height: 20px;text-align: center;vertical-align: middle;cursor: pointer;
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2), 0 1px 2px rgba(0, 0, 0, 0.05);
    border-radius: 4px;}
  .btn-danger {color: #fff;background-color: #da4f49;border: 1px solid #bd362f;}
  .btn-danger:hover {color: #fff;background-color: #bd362f;}
  .btn:focus {outline: none;}
  .todo-container {width: 600px;margin: 0 auto;}
  .todo-container .todo-wrap {padding: 10px;border: 1px solid #ddd;border-radius: 5px;}
</style>

src/MyHeader.vue

<template>
	<div class="todo-header">
		<input 	type="text" 
						placeholder="请输入你的任务名称，按回车键确认" 
						@keydown.enter="add"
						v-model="title"
						/>
	</div>
</template>

<script>
	export default {
		name:'MyHeader',
		props:['addTodo'],
		data(){
			return {
				title:''
			}
		},
		methods:{
			add(e){
				const val = e.target.value;
				if (! val.trim()) {
					alert('输入内容为空')
				} else {
					this.addTodo(val)
					this.title = ''
				}
			}
		}
	}
</script>

<style scoped>
	/*header*/
	.todo-header input {width: 560px;height: 28px;font-size: 14px;
    border: 1px solid #ccc;border-radius: 4px;padding: 4px 7px;}
	.todo-header input:focus {outline: none;border-color: rgba(82, 168, 236, 0.8);
		box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 8px rgba(82, 168, 236, 0.6);}
</style>

src/MyList.vue

<template>
  <ul class="todo-main">
   <MyItem v-for="todoObj in todos" 
      :key="todoObj.id" 
      :todoObj="todoObj" 
      :changeState="changeState" 
      :deleteTodo="deleteTodo"
    />
  </ul>
</template>

<script>
  import MyItem from './MyItem.vue';
  export default {
    name:'MyList',
    props:['todos', 'changeState', 'deleteTodo'],
    components:{MyItem}
  }
</script>

<style scoped>
  /*main*/
  .todo-main {margin-left: 0px;border: 1px solid #ddd;border-radius: 2px;padding: 0px;}
  .todo-empty {height: 40px;line-height: 40px;border: 1px solid #ddd;
    border-radius: 2px;padding-left: 5px;margin-top: 10px;}
</style>

src/MyItem.vue

<template>
  <li>
    <label @click="change(todoObj.id)">
      <!-- 如下代码也能实现功能，但是不太推荐，因为有点违反原则，因为修改了props -->
      <!-- <input type="checkbox" v-model="todo.done"/> -->
      <input type="checkbox" :checked="todoObj.done" @change="change(todoObj.id)" />  
      <span>{{todoObj.title}}</span>
    </label>
    <button class="btn btn-danger" @click="deleteTodoObj(todoObj.id)">删除</button>
  </li>
</template>

<script>
  export default {
    name:'MyItem',
    props:['todoObj', 'changeState', 'deleteTodo'],
    methods:{
      change(id) {
        this.changeState(id)
      },
      deleteTodoObj(id) {
        if (id) this.deleteTodo(id)
      }
    }
  }
</script>

<style scoped>
  /*item*/
  li {list-style: none;height: 36px;line-height: 36px;padding: 0 5px;
    border-bottom: 1px solid #ddd;}
  li label {float: left;cursor: pointer;}
  li label li input {vertical-align:middle; margin-right:6px; position:relative;top: -1px;}
  li button {float: right;display: none;margin-top: 3px;}
  li:before {content: initial;}
  li:last-child {border-bottom: none;}
  li:hover{background-color: #ddd;}
  li:hover button{display: block;}
</style>

src/MyFooter.vue

<template>
  <div class="todo-footer" v-show="total">
    <label>
      <!-- <input type="checkbox" :checked="isAll" @change="checkAll"/> -->
      <input type="checkbox" v-model="c" />
    </label>
    <span>
      <span>已完成{{done}}</span> / 全部{{total}}
    </span>
    <button class="btn btn-danger" @click="deleteDones">清除已完成任务</button>
  </div>
</template>

<script>
  export default {
    name:'MyFooter',
    props:['allCheck', 'getNum', 'getDoneNum', 'deleteDone'],
    computed:{
      total:{
        get(){
          return this.getNum()
        }
      },
      done:{
        get(){
          return this.getDoneNum()
        },
      },
      c:{
        get(){
          return this.total === this.done ? true : false
        },
        set(value){
          this.allCheck(value)
        }
      }
    },
    methods:{
      deleteDones(){
        this.deleteDone()
      }
    }
  }
</script>

<style scoped>
  /*footer*/
  .todo-footer {height: 40px;line-height: 40px;padding-left: 6px;margin-top: 5px;}
  .todo-footer label {display: inline-block;margin-right: 20px;cursor: pointer;}
  .todo-footer label input {position: relative;top: -1px;vertical-align: middle;
    margin-right: 5px;}
  .todo-footer button {float: right;margin-top: 5px;}
</style>