1. 添加购物车

基础思想：如果已经添加过相同的商品，就在其数量count上加一，如果没有添加过，就直接push到购物车列表中

cart.js

// 封装购物车模块

import { defineStore } from 'pinia'
import { ref } from 'vue'

export const useCartStore = defineStore('cart', () => {
  // 1. 定义state - cartList
  const cartList = ref([])
  // 2. 定义action - addCart
  const addCart = (goods) => {
    console.log('添加', goods)
    // 添加购物车操作
    // 已添加过 - count + 1
    // 没有添加过 - 直接push
    // 思路：通过匹配传递过来的商品对象中的skuId能不能在cartList中找到，找到了就是添加过
    const item = cartList.value.find((item) => goods.skuId === item.skuId)
    if (item) {
      // 找到了
      item.count++
    } else {
      // 没找到
      cartList.value.push(goods)
    }
  }
  return {
    cartList,
    addCart
  }
}, {
  persist: true,
})

调用这个方法

// sku规格被操作时，获取这个sku
let skuObj = {}
const skuChange = (sku) => {
  skuObj = sku
  console.log(skuObj)
}

const cartStore = useCartStore()
const count = ref(1);
const countChange = () => {
  console.log(count);
}

const addCart = () => {
  if(skuObj.skuId) {
    cartStore.addCart({
        id: goods.value.id,
        name: goods.value.name,
        picture: goods.value.mainPictures[0],
        price: goods.value.price,
        count: count.value,
        skuId: skuObj.skuId,
        attrsText: skuObj.specsText
      })
  } else {
    ElMessage.warning("请选择规格")
  }
}

绑定这两个方法

<!-- 数据组件 -->
<el-input-number v-model="count" @change="countChange()"> </el-input-number>
<!-- 按钮组件 -->
<div>
  <el-button size="large" class="btn" @click="addCart">
    加入购物车
  </el-button>
</div>

2. 头部购物车

2.1. 头部购物车组件模版

<script setup>

</script>

<template>
  <div class="cart">
    <a class="curr" href="javascript:;">
      <i class="iconfont icon-cart"></i><em>2</em>
    </a>
    <div class="layer">
      <div class="list">
        <!--
        <div class="item" v-for="i in cartList" :key="i">
          <RouterLink to="">
            <img :src="i.picture" alt="" />
            <div class="center">
              <p class="name ellipsis-2">
                {{ i.name }}
              </p>
              <p class="attr ellipsis">{{ i.attrsText }}</p>
            </div>
            <div class="right">
              <p class="price">¥{{ i.price }}</p>
              <p class="count">x{{ i.count }}</p>
            </div>
          </RouterLink>
          <i class="iconfont icon-close-new" @click="store.delCart(i.skuId)"></i>
        </div>
        -->
      </div>
      <div class="foot">
        <div class="total">
          <p>共 10 件商品</p>
          <p>¥ 100.00 </p>
        </div>
        <el-button size="large" type="primary" >去购物车结算</el-button>
      </div>
    </div>
</div>
</template>

<style scoped lang="scss">
.cart {
  width: 50px;
  position: relative;
  z-index: 600;

  .curr {
    height: 32px;
    line-height: 32px;
    text-align: center;
    position: relative;
    display: block;

    .icon-cart {
      font-size: 22px;
    }

    em {
      font-style: normal;
      position: absolute;
      right: 0;
      top: 0;
      padding: 1px 6px;
      line-height: 1;
      background: $helpColor;
      color: #fff;
      font-size: 12px;
      border-radius: 10px;
      font-family: Arial;
    }
  }

  &:hover {
    .layer {
      opacity: 1;
      transform: none;
    }
  }

  .layer {
    opacity: 0;
    transition: all 0.4s 0.2s;
    transform: translateY(-200px) scale(1, 0);
    width: 400px;
    height: 400px;
    position: absolute;
    top: 50px;
    right: 0;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
    background: #fff;
    border-radius: 4px;
    padding-top: 10px;

    &::before {
      content: "";
      position: absolute;
      right: 14px;
      top: -10px;
      width: 20px;
      height: 20px;
      background: #fff;
      transform: scale(0.6, 1) rotate(45deg);
      box-shadow: -3px -3px 5px rgba(0, 0, 0, 0.1);
    }

    .foot {
      position: absolute;
      left: 0;
      bottom: 0;
      height: 70px;
      width: 100%;
      padding: 10px;
      display: flex;
      justify-content: space-between;
      background: #f8f8f8;
      align-items: center;

      .total {
        padding-left: 10px;
        color: #999;

        p {
          &:last-child {
            font-size: 18px;
            color: $priceColor;
          }
        }
      }
    }
  }

  .list {
    height: 310px;
    overflow: auto;
    padding: 0 10px;

    &::-webkit-scrollbar {
      width: 10px;
      height: 10px;
    }

    &::-webkit-scrollbar-track {
      background: #f8f8f8;
      border-radius: 2px;
    }

    &::-webkit-scrollbar-thumb {
      background: #eee;
      border-radius: 10px;
    }

    &::-webkit-scrollbar-thumb:hover {
      background: #ccc;
    }

    .item {
      border-bottom: 1px solid #f5f5f5;
      padding: 10px 0;
      position: relative;

      i {
        position: absolute;
        bottom: 38px;
        right: 0;
        opacity: 0;
        color: #666;
        transition: all 0.5s;
      }

      &:hover {
        i {
          opacity: 1;
          cursor: pointer;
        }
      }

      a {
        display: flex;
        align-items: center;

        img {
          height: 80px;
          width: 80px;
        }

        .center {
          padding: 0 10px;
          width: 200px;

          .name {
            font-size: 16px;
          }

          .attr {
            color: #999;
            padding-top: 5px;
          }
        }

        .right {
          width: 100px;
          padding-right: 20px;
          text-align: center;

          .price {
            font-size: 16px;
            color: $priceColor;
          }

          .count {
            color: #999;
            margin-top: 5px;
            font-size: 16px;
          }
        }
      }
    }
  }
}
</style>

2.2 渲染头部购物车数据

<script setup>
import { useCartStore } from '@/stores/cart'
const cartStore = useCartStore()

</script>

<template>
  <div class="cart">
    <a class="curr" href="javascript:;">
      <i class="iconfont icon-cart"></i><em>{{ cartStore.cartList.length }}</em>
    </a>
    <div class="layer">
      <div class="list">

        <div class="item" v-for="i in cartStore.cartList" :key="i">
          <RouterLink to="">
            <img :src="i.picture" alt="" />
            <div class="center">
              <p class="name ellipsis-2">
                {{ i.name }}
              </p>
              <p class="attr ellipsis">{{ i.attrsText }}</p>
            </div>
            <div class="right">
              <p class="price">¥{{ i.price }}</p>
              <p class="count">x{{ i.count }}</p>
            </div>
          </RouterLink>
          <i class="iconfont icon-close-new" @click="cartStore.delCart(i.skuId)"></i>
        </div>

      </div>
      <div class="foot">
        <div class="total">
          <p>共 {{ cartStore.allCount }} 件商品</p>
          <p>¥ {{ cartStore.allPrice.toFixed(2) }} </p>
        </div>
        <el-button size="large" type="primary" @click="$router.push('/cartlist')">去购物车结算</el-button>
      </div>
    </div>
</div>
</template>

2.3 删除功能实现

1- 添加删除action函数

// 删除购物车
  const delCart = async (skuId) => {
      // 思路：
      // 1. 找到要删除项的下标值 - splice
      // 2. 使用数组的过滤方法 - filter
      const idx = cartList.value.findIndex((item) => skuId === item.skuId)
      cartList.value.splice(idx, 1)
  }

2- 组件触发action函数并传递参数

<i class="iconfont icon-close-new" @click="cartStore.delCart(i.skuId)"></i>

2.4 金额总和实现

const allCount = computed(()=> cartList.value.reduce((a,c)=>a+c.count, 0))
const allPrice = computed(()=> cartList.value.reduce((a,c)=>a+c.count*c.price, 0))