待练习 

记得写key 

        <tbody>
          <tr v-for="(item, index) in books"
              :key="item.id"
              @click="rowClick(index)"
              :class="{ active: index === currentIndex }">
            <td>{{ index + 1 }}</td>
            <td>{{ item.name }}</td>
            <td>{{ item.date }}</td>
            <td>{{ formatPrice(item.price) }}</td>
            <td>
              <button :disabled="item.count <= 1" @click="decrement(index, item)">-</button>
              {{ item.count }}
              <button @click="increment(index, item)">+</button>
            </td>
            <td>
              <button @click="removeBook(index, item)">移除</button>
            </td>
          </tr>
        </tbody>