利用vue3自己实现计数功能组件封装实例

<template>
  <div class="my-numbox">
    <div class="label">
      <slot>数量</slot>
    </div>
    <div class="numbox">
      <a href="javascript:;" @click="toggle(-1)" :class="{notallow: modelValue === 1}">-</a>
      <input type="text" readonly :value="num">
      <a href="javascript:;" @click="toggle(1)" :class="{notallow: modelValue === inventory}">+</a>
    </div>
  </div>
</template>
<script>
import { useVModel } from '@vueuse/core'
export default {
  name: 'MyNumbox',
  props: {
    modelValue: {
      type: Number,
      default: 1
    },
    inventory: {
      type: Number,
      required: true
    }
  },
  setup (props, { emit }) {
    // 基于第三方的方法控制数据的双向绑定
    const num = useVModel(props, 'modelValue', emit)
    // 控制商品数据的变更操作
    const toggle = (n) => {
      if (n < 0) {
        // 减一操作
        if (num.value > 1) {
          num.value -= 1
        }
      } else {
        // 加一操作
        if (num.value < props.inventory) {
          num.value += 1
        }
      }
    }
    return { num, toggle }
  }
}
</script>
<style scoped lang="less">
.my-numbox {
  display: flex;
  align-items: center;
  .notallow {
    cursor: not-allowed;
  }
  .label {
    width: 60px;
    color: #999;
    padding-left: 10px;
  }
  .numbox {
    width: 120px;
    height: 30px;
    border: 1px solid #e4e4e4;
    display: flex;
    > a {
      width: 29px;
      line-height: 28px;
      text-align: center;
      text-decoration: none;
      background: #f8f8f8;
      font-size: 16px;
      color: #666;
      &:first-of-type {
        border-right:1px solid #e4e4e4;
      }
      &:last-of-type {
        border-left:1px solid #e4e4e4;
      }
    }
    > input {
      width: 60px;
      padding: 0 5px;
      text-align: center;
      color: #666;
    }
  }
}
</style>

<template>
  <div class="home-banner">
    <MyNumbox v-model="num" :inventory="5">件数：</MyNumbox>
  </div>
</template>

<script>
import { ref } from 'vue'
export default {
  name: 'App',
  setup () {
    const num = ref(1)
    return { num }
  }
}
</script>

<style lang="less">
.home-banner {
  margin: 100px auto;
  width: 500px;
  height: 100px;
}
</style>