一、效果：

如下图所示，进入该页面后，默认选中第一个分类，以及第一个分类下的列表数据。

二、代码实现：

关键代码：

进入页面时，默认调用分类的接口，在分类接口里做判断：

if (that.TabIndex == 0) { //默认选中第一个分类下的数据that.cate_id = that.cateList[0].idthat.getListFun(that.cate_id)
}

完整代码：

<template><view class="">//1分类展示<scroll-view :scroll-x="true" class="scrollview-box"><block v-for="(item,index) in cateList" :key="item"><view :class="TabIndex==index?'item active':'item'" @click="tabclick(index,item)">{{item.name}}</view></block></scroll-view>//2列表展示<view class="invenlist" v-if="storeList.length>0"><view class="invenitem" v-for="(item,index) in storeList" :key="index"><view>{{item.name}}</view></view></view></view>
</template><script>export default {data() {return {//分类cateList: [],cate_id:'',TabIndex: 0,//默认第一个分类//列表数据storeList: [],}},onShow() {//进入页面，默认调用分类接口this.getCateFun() },methods: {//1.分类接口			getCateFun() {var that = thisthis.$api.appPlateForm('POST', this.$url.products_cate_list, '', function(res) {that.cateList = res.data  //获取分类数据if (that.TabIndex == 0) { //默认选中第一个分类下的数据that.cate_id = that.cateList[0].idthat.getListFun(that.cate_id)}})},//2.列表接口	getListFun(id) {var that = thisvar data = {cate_id:id}this.$api.appPlateForm('POST', this.$url.products_store_list, data, function(res) {that.storeList = res.data   //获取列表数据})},// tab切换tabclick(index,item) {var that = thisthat.TabIndex = index;that.cate_id = item.idvar data = {cate_id:that.cate_id}//获取到id，调用列表接口this.$api.appPlateForm('POST', this.$url.products_store_list, data, function(res) {that.storeList = res.data   //获取列表数据})},}}
</script><style scoped lang="less">.scrollview-box {white-space: nowrap;/* 滚动必须加的属性 */width: 100%;padding:0 20rpx;box-sizing: border-box;.item {width: 180rpx;height:50rpx;margin-right: 20rpx;display: inline-flex;/* item的外层定义成行内元素才可进行滚动 inline-block / inline-flex 均可 */flex-direction: column;align-items: center;font-size: 28rpx;color: #666666;position: relative;}view::after{display: block;clear: both;content: '';position: absolute;bottom: 0;left: 0;right: 0;margin: auto;height: 4rpx;width: 145rpx;background-color:  #21CD81;display: none;}.active {font-weight: bold !important;color: #21CD81 !important;}.active::after{display: block;}}
</style>