根据上面所写设想出自己的图书购买清单:

<div id="books">
  <table>
    <tr>
      <th>序列号</th>
      <th>书名</th>
      <th>价格</th>
      <th>数量</th>
      <th>操作</th>
    </tr>
    <tr v-for="book in Books">
      <td>{{ book.id }}</td>
      <td>{{ book.book_name }}</td>
      <td>{{ book.price }}</td>
      <td>
        <button v-on:click="book.count-=1">-</button>
        {{ book.count }}
        <button v-on:click="book.count+=1">+</button>
      </td>
      <td><button v-on:click="book.count=0">移除</button></td>
    </tr>
  </table>
 
<p>总价:{{ totalPrice() }}   <button v-on:click="clear()">移除所有</button>  <button v-on:click="all_add_1()">所有+1</button></p>
</div>

尝试一下 »

参考楼上，购物车进行加工处理（computed也可实现相同效果，且由于其依赖缓存，所以性能上更好）：

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="https://cdn.staticfile.org/vue/2.2.2/vue.min.js"></script>
</head>
<body>
  <div id="app">
    <table>
      <tr>
        <th>序号</th>
        <th>商品名称</th>
        <th>商品价格</th>
        <th>购买数量</th>
        <th>操作</th>
      </tr>
      <tr v-for="(c, index) in commoditys" :key="index">
        <td>{{ c.id }}</td>
        <td>{{ c.name }}</td>
        <td>{{ c.price | dot }}</td>
        <td>
          <input type="button" value="-" :disabled="c.count === 0" @click="c.count > 0 ? c.count-- : c.count = 0" />
          {{ c.count }}
          <input type="button" value="+" @click="c.count++" />
        </td>
        <td>
          <input type="button" value="移除" @click="c.count=0" />
        </td>
      </tr>
    </table>
    <div>
      总价：${{ totalPrice | dot }}
      <input type="button" value="清空" @click="clearAll" />
      <input type="button" value="所有+1" @click="add" />
    </div>
  </div>
  <script>
    const app = new Vue({
      // 挂载元素
      el: '#app',
      // 数据
      data: {
        commoditys: [
          {
            id: 1,
            name: 'iphone 8',
            price: 5099,
            count: 0
          },
          {
            id: 2,
            name: 'iphone xs',
            price: 8699,
            count: 0
          },
          {
            id: 3,
            name: 'iphone xr',
            price: 6499,
            count: 0
          }
        ]
      },
      // 方法
      methods: {
        clearAll() {
          const len = this.commoditys.length;
          for (let i = 0; i < len; i++) {
            this.commoditys[i].count = 0;
          }
        },
        add() {
          const len = this.commoditys.length;
          for (let i = 0; i < len; i++) {
            this.commoditys[i].count++;
          }
        }
      },
      // 计算属性
      computed: {
        totalPrice() {
          let sum = 0;
          const len = this.commoditys.length;
          for (let i = 0; i < len; i++) {
            sum += this.commoditys[i].price * this.commoditys[i].count;
          }
          return sum;
        }
      },
      // 过滤器
      filters: {
        dot(val) {  // 简单处理保留两位小数
          return `${val}.00`;
        }
      }
    });
  </script>  
</body>
</html>