事件绑定

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>事件绑定</title>
    <script src="https://unpkg.com/vue@next"></script>
</head>
<body>
    <!-- es6 -->
    <p> 
       <!-- <a href="https://www.baidu.com" onclick = "showURL( )">URL地址跳转  </a> -->
                                                                   <!-- 事件属性 -->
         <a href="https://www.php.cn" onclick="showUrl()">显示地址一 : </a>
        <span  class="url"> </span>
    </p>
        <!-- vue -->
        <div class="app">
        <p >
            <!-- <a href="https://www.baidu.com" onclick = "showURL( )">URL地址跳转  </a>
             -->
                                                         <!-- 事件属性   v-on    @  -->
             <a href="https://www.php.cn" @click="showUrl1($event)">显示地址二 : </a>
            <span  class="url1">{{url1}} </span>
        </p>
    </div>
<!-- 简化 -->
<div class="app">
    <p  onclick="   console.log(   '你好呀');">
        <!-- <a href="https://www.baidu.com" onclick = "showURL( )">URL地址跳转  </a>
         -->
                                                     <!-- 事件属性   v-on    @  -->
         <a href="https://www.php.cn" @click="showUrl2($event)">显示地址三 : </a>
        <span  class="url2">{{url2}} </span>
    </p>
</div>
    <script>
    // 为事件属性绑定 事件方法
        function showUrl(){
        //    禁用跳转行为
        event.preventDefault();
        console.log(   EventTarget);
        console.log(event.target);
        console.log(event.target.href);
        console.log(event.currentTarget);
        console.log(event.currentTarget.href);
        console.log('=======================');
        // 获取下一个兄弟节点event.nextElementSibling.textConent     
        console.log(event.target.nextElementSibling);
        // 下一个兄弟节点内容修改   
//   event.target.nextElementSibling.textContent = event.target.href;
  console.log('+++++++++++++++++++++++++++++');
     }
                   </script>
                   <!-- // 为事件属性绑定 事件方法  VUE -->
                   <script>
     Vue.createApp({
        //  实例数据
        data() {
            return {
                // 插值变量
                url1: null,  
            };
        },
    // 事件方法
    methods: {
        showUrl1( ev){
            ev.preventDefault();
            console.log(ev);
            console.log(ev.target.href);      
            console.log(ev.currentTarget.href);      
            this.url1 = ev.currentTarget.href;
        },
    },
       }).mount('.app');
                   </script>
</body>
</html>

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>事件绑定</title>
    <script src="https://unpkg.com/vue@next"></script>
</head>
<body>
    <div class="app">
        <p  onclick="   console.log(   '你好呀');">
            <!-- <a href="https://www.baidu.com" onclick = "showURL( )">URL地址跳转  </a>
             -->
                                                         <!-- 事件属性   v-on    @  -->
             <a href="https://www.php.cn" @click.prevent.stop="showUrl2($event)">显示地址三 : </a>
            <span  class="url2">{{url2}} </span>
        </p>
    </div>
       <!-- // 为事件属性绑定 事件方法  VUE -->
       <script>
        Vue.createApp({
           //  实例数据
           data() {
               return {
                   // 插值变量
                   url2: null,  
               };
           },
       // 事件方法
       methods: {
           showUrl2( ev){
            // 其中   ev.preventDefault();和 ev.stopPropagation();  可以简化 用修饰符简化， 如 @click.prevent.stop="showUrl2($event)"
             //    去掉时间点击跳转行为
            //    ev.preventDefault();
            //    去掉冒泡行为
            //    ev.stopPropagation();
               console.log(ev);
               console.log(ev.target.href);      
               console.log(ev.currentTarget.href);      
               this.url2 = ev.currentTarget.href;
           },
       },
          }).mount('.app');
                      </script>
</body>
</html>

列表渲染（数组、关联数组）

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>列表渲染（数组、关联数组）</title>
    <script src="https://unpkg.com/vue@next"></script>
</head>
<body>
<div class="app">
       <!-- 数组 array -->
       <p>{{cities}}</p>
       <p>{{cities[1]}}</p>
       <ul>
        <li>{{cities[1]}}</li>
        <li>{{cities[2]}}</li>
       </ul>
       <!-- fot of 循环数组 
     for(let item of array) {
     }
    -->
       <!-- v-for ：指令循环输出 -->
       <ul>
        <li  v-for="city of cities">{{city}}</li>
       </ul>
       <ul>
        <!-- index    是键 key ，可以激发diff算法    city是值value       :key 等于 v-bind:key -->
                                            <!-- 注意 of前后空格 -->
        <li  v-for="(city,index) of cities"  :key="index">{{index}}:{{city}}</li>
       </ul>
       console.log('=====');
       <p>{{cities}}</p>
       <hr>
       <!-- v-for   对象数组 -->
       <ul>
                                  <!-- prop属性 -->
        <li  v-for="(user,prop,index) of users"  :key="index">{{index}}:{{user}}</li>
        <li  v-for="(user,prop,index) of users"  :key="index">{{user.name}},{{user.email}}</li>
       </ul>
       <hr>
       <ul>
         <!--    对象 -->
<li  >{{user.name}}：{{user.email}}</li>
</ul>
</div>
    <script>
    const app = Vue.createApp({
    data() {
        return {
            // 数组  array 
            cities:['1','2','3','4','5'],
            //  对象  object    关联数组 
            user:{
                name:'小狗',
                email:'123@qq.com',
            },
            // 对象数组 array of object
            users :[
            {
                name:'小猫',
                email:'123@qq.com',
            },
            {
                name:'小牛',
                email:'123@qq.com',
            },
            ],
            }
        },
    }, ).mount('.app');
    </script>
</body>
</html>

条件渲染v-if

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>条件渲染v-if</title>
    <script src="https://unpkg.com/vue@next"></script>
</head>
<body>
    <div class="app">
      <p>{{message}}</p>
      <p  v-if = 'true'>{{message}}，ture显示</p>
      <p  v-if = 'false'>{{message}}，false不显示</p>
      <p  v-if = 'flag'>{{message}}</p>
      <!-- 开关控制 -->
      <!-- <button>隐藏</button> -->
     <hr>
     <button v-text = 'flag?"隐藏":"显示"'></button>
     <br>
     <button v-text = 'flag1?"隐藏":"显示"'></button>
     <hr>
     <p  v-if = 'flag'>{{message}}</p>
     <button @click = 'flag=!flag' v-text = 'flag1?"隐藏":"显示"'></button>
    <hr>
     <!-- if -else   if     else  if   else   -->
     <!-- <p v-if ='point'>{{grade[4]}}</p> -->
     console.log('=======');<br>
     <p v-if ='point>100 && point< 1000'>{{grade[0]}}</p>
     <!-- console.log('=======');<br>   条件判断中间不能加其他的标签 -->
     <p v-else-if='point>=2000 && point< 3000'>{{grade[1]}}</p>
     <p v-else-if="point>=3000 && point< 4000">{{grade[2]}}</p>
     <p v-else-if="point>=5000 && point< 6000">{{grade[3]}}</p>
     <!-- <p v--else-if="point>=4000 && point< 5000">{{grade[3]}}</p> -->
     <p v-else>{{grade[4]}}</p>
    </div>
<script>
const app = Vue.createApp({
    data() {
        return {
              message:'今天好热',
            //   true 显示   false 不显示    style = display: none
              flag :true,
              flag1 :false,
              grade:['普通','银卡','金卡','白金','非会员'],
              point:5100,
        };
    },
}).mount('.app');
</script>
</body>
</html>

修饰符

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://unpkg.com/vue@next"></script>
</head>
<body>
    <div class="app">
  <!-- <input type="text"  @keydown = 'submit($event)'> -->
  <!-- enter  键盘修饰符    回车-->
  <input type="text"  @keydown.enter = 'submit($event)'>
  <ul>
      <!-- :key  为了增加渲染的效率 -->
    <li v-for="(item ,index) of list"   :key="index">{{item}}  </li>
  </ul>
    </div>
    <script>
 Vue.createApp({
data() {
    return {
        // 留言列表
   list:[],
    };
},
methods: {
          submit(ev) {
            console.log(ev);
            if (ev.key === 'Enter') {
            //   this.list.unshift(ev.currentTarget.value);
            //   ev.currentTarget.value = null;
            }
            this.list.unshift(ev.currentTarget.value);
            ev.currentTarget.value = null;
          },
        },
// methods: {
//     submit:(ev){
//         console.log(ev);
//         if (ev.key =='Enter'){
//             this.List.unshift(ev.currentTarget.value);
//         }
//     }
// },
}).mount('.app');
    </script>
</body>
</html>

计算属性，侦听器属性

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>计算属性，侦听器属性</title>
    <script src="https://unpkg.com/vue@next"></script>
</head>
<style>
    table {
      width: 20em;
      height: 10em;
      text-align: center;
      border-collapse: collapse;
      margin: 1em;
    }
    table caption {
      font-size: 1.2em;
      padding: 1em;
      margin-bottom: 2em;
      border-bottom: 1px solid;
    }
    tbody tr th:first-of-type {
      background: linear-gradient(to left, lightcyan, #fff);
      border-right: 1px solid;
    }
    body tbody tr:not(:last-of-type) > * {
      border-bottom: 1px solid;
    }
  </style>
</head>
<body>
  <div class="app">
    <table>
      <caption>
        商品结算
      </caption>
      <tbody>
        <tr>
          <th>ID</th>
          <td>HA110</td>
        </tr>
        <tr>
          <th>品名</th>
          <td>伊利纯牛奶</td>
        </tr>
        <tr>
          <th>单价</th>
          <td>100</td>
        </tr>
        <tr>
          <th>数量</th>
                                                       <!-- v- modle 双向绑定 -->
          <td><input type="number" v-model="num" style="width: 5em" /></td>
        </tr>
        <tr>
          <th>金额</th>
          <!-- <td>{{num * price}}</td> -->
          <td>{{amount}}</td>
        </tr>
      </tbody>
    </table>
    <p style="font-size: 1.2em">
        实付金额: {{realAmount}}
      <br>
        优惠了 :
        <span style="color: red">{{difAmount}}</span>
      </p>
  </div>
  <script>
    const app = Vue.createApp({
        data() {
            return {
            // 单价
            price: 100,
            // 数量
            num: 0,
            // 折扣
            discount: 1,
          // 实际金额
        //   realAmount:100,
        //   优惠金额
        difAmount:0,
            };
        },
        // 计算器属性
        computed:{
        //  计算属性金额 = 单价乘以数量
        // get amount(){
        // },
        amount:{
        get(){
      return this.price * this.num;
        },
        set (value){
        },
        },
        },
        // 侦听器属性
        watch:{
        //    访问器属性实现。看着是属性，实际是方法
        // 被侦听的 属性其实一个方法  有两个参数组装，第一是 新值当前值  第二个值是原来的值，以前的旧值
            amount( current,origin){
                // console.log('当前'+ current ,'旧值'+origin);
                  // 根据当前金额确定打折
                  switch (true) {
              // 1000-2000: 9折
              case current >= 1000 && current < 2000:
                this.discount = 0.9;
                break;
              // 2000 -> 3000 : 8折
              case current >= 2000 && current < 3000:
                this.discount = 0.8;
                break;
              // 3000 -> 4000 : 7折
              case current >= 3000 && current < 4000:
                this.discount = 0.7;
                break;
              // 4000 -> 5000 : 6折
              case current >= 4000 && current < 5000:
                this.discount = 0.6;
                break;
              // 5000 : 5折
              case current >= 5000:
                this.discount = 0.5;
            } 
                                        //    实付金额 =原始金额*折扣率
            // this.realAmount =  this.amount  * this.discount;
            // 优惠金额（差价）  =原始金额 -实付金额
            // this.difAmount =  this.amount   -    this.realAmount ;     
                        // 实付金额 = 原始金额 * 折扣率
                        this.realAmount = this.amount * this.discount;
                         console.log(this.realAmount);
// 优惠金额(差价) = 原始金额 - 实付金额
this.difAmount = this.amount - this.realAmount;
            },
        },
          // 实例的声明周期，当实例与挂载点绑定成功时，自动执行
  mounted(){
        this.num =1;
      }
        // 挂载
    }).mount('.app');
  </script>
</body>
</html>

Correcting teacher：

PHPz

Correction status：qualified

Teacher's comments：

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