SOURCE

    // # 1、 把静态页面转换成组件化模式
    // 1.1  标题组件 
    var CartTitle = {
      template: `
            <div class="title">{{uname}}</div>
          `,
      props: ['uname']
    }
    // 1.2  商品列表组件 
    var CartList = {
      props: ['list'],
      //  注意点 ：  组件模板必须是单个根元素  
      template: `
      <div>
            <div class="item" v-for="item in list" :key="item.id">
                <img :src="item.img" />
                <div class="name">{{item.name}}</div>
                <div class="change">
                    <a href="" @click.prevent="sub(item.id)">－</a>
                    <input type="text" class="num" :value='item.num' @blur='changeNum(item.id,$event)' />
                    <a href="" @click.prevent="add(item.id)">＋</a>
                </div>
                <div class="del" @click="del(item.id)">×</div>
            </div>
      </div>
          `,


      methods: {
        del: function (id) {
          this.$emit('cart-del', id)
        },
        changeNum: function (id, event) {
          this.$emit('change-num', {
            id: id,
            num: event.target.value,
            type: 'change'
          })
        },
        sub: function (id) {
          this.$emit('change-num', {
            id: id,
            type: 'sub'
          })
        },
        add: function (id) {
          this.$emit('change-num', {
            id: id,
            type: 'add'
          })
        }
      }
    }
    // 1.3  商品结算组件 
    var CartTotal = {
      template: `
            <div class="total">
              <span>总价：{{total}}</span>
              <button>结算</button>
            </div>
          `,
      props: ['list'],
      computed: {
        total: function () {
          var t = 0;
          this.list.forEach(item => {
            t += item.price * item.num;
          })
          return t;
        }
      }
    }
    //# 1.4  定义一个全局组件 my-cart
    Vue.component('my-cart', {
      data: function () {
        return {
          uname: '张三',
          list: [{
            id: 1,
            name: 'TCL彩电',
            price: 1000,
            num: 1,
            img: 'https://i.loli.net/2021/03/28/vRHBhsUgyCTnMfw.jpg'
          }, {
            id: 2,
            name: '机顶盒',
            price: 1000,
            num: 1,
            img: 'https://i.loli.net/2021/03/28/pE5vDX2nfd1AOFh.jpg'
          }, {
            id: 3,
            name: '海尔冰箱',
            price: 1000,
            num: 1,
            img: 'https://i.loli.net/2021/03/28/89iQr6GtpUDMoYJ.jpg'
          }, {
            id: 4,
            name: '小米手机',
            price: 1000,
            num: 1,
            img: 'https://i.loli.net/2021/03/28/7S23tueqP5sinAr.jpg'
          }, {
            id: 5,
            name: 'PPTV电视',
            price: 1000,
            num: 2,
            img: 'https://i.loli.net/2021/03/28/kIoaPnr19MXQZbT.jpg'
          }]
        }
      },
      // 1.5  注册子组件   
      components: {
        'cart-title': CartTitle,
        'cart-list': CartList,
        'cart-total': CartTotal
      },
      //#  1.6 引入子组件  
      template: `
            <div class='cart'>
              <cart-title :uname="uname"></cart-title>
              <cart-list :list="list" @cart-del='delCart($event)' @change-num='changeNum($event)'></cart-list>
              <cart-total :list=list></cart-total>
            </div>
          `,

      methods: {
        delCart: function (id) {
          var index = this.list.findIndex(item => {
            return item.id == id;
          });
          this.list.splice(index, 1);
        },
        changeNum: function (val) {

          if (val.type == 'change') {
            this.list.some(item => {
              if (item.id == val.id) {
                item.num = parseInt(val.num);
                return true;
              }
            })
          } else if (val.type == 'sub') {
            this.list.some(item => {
              if (item.id == val.id) {
                item.num -= 1;
                return true;
              }
            })
          } else if (val.type == 'add') {
            this.list.some(item => {
              if (item.id == val.id) {
                item.num += 1;
                return true;
              }
            })
          }
        },
      }
    });

    var vm = new Vue({
      el: '#app',
      data: {

      }
    });

  <div id="app">
    <div class="container">
      <!-- 2、把组件渲染到页面上 -->
      <my-cart></my-cart>
    </div>
  </div>
  <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>

.container .cart {
  width: 300px;
  margin: auto;
}

.container .title {
  background-color: lightblue;
  height: 40px;
  line-height: 40px;
  text-align: center;
  /*color: #fff;*/
}

.container .total {
  background-color: #FFCE46;
  height: 50px;
  line-height: 50px;
  text-align: right;
}

.container .total button {
  margin: 0 10px;
  background-color: #DC4C40;
  height: 35px;
  width: 80px;
  border: 0;
}

.container .total span {
  color: red;
  font-weight: bold;
}

.container .item {
  height: 55px;
  line-height: 55px;
  position: relative;
  border-top: 1px solid #ADD8E6;
}

.container .item img {
  width: 45px;
  height: 45px;
  margin: 5px;
}

.container .item .name {
  position: absolute;
  width: 90px;
  top: 0;
  left: 55px;
  font-size: 16px;
}

.container .item .change {
  width: 100px;
  position: absolute;
  top: 0;
  right: 50px;
}

.container .item .change a {
  font-size: 20px;
  width: 30px;
  text-decoration: none;
  background-color: lightgray;
  vertical-align: middle;
}

.container .item .change .num {
  width: 40px;
  height: 25px;
}

.container .item .del {
  position: absolute;
  top: 0;
  right: 0px;
  width: 40px;
  text-align: center;
  font-size: 40px;
  cursor: pointer;
  color: red;
}

.container .item .del:hover {
  background-color: orange;
}