scroll-view通过query获取高度的问题

<template>
    <scroll-view id="scrollview" scroll-y="true" :style="{height:scrollHeight+'px'}" :scroll-top="scrollTop"
   </scroll-view>
</template>

如果scroll-view外层没有view或者其他元素包住的话，query查询的话会是null
let query = uni.createSelectorQuery().in(this)
query.select('#scrollview').boundingClientRect()

query.exec((res) => {
//res会是null
});

<template>
     <view>
    <scroll-view id="scrollview" scroll-y="true" :style="{height:scrollHeight+'px'}" :scroll-top="scrollTop"
   </scroll-view>
    </view>
</template>

如果scroll-view外层有内容包住之后，query才能查询出来信息
let query = uni.createSelectorQuery().in(this)
query.select('#scrollview').boundingClientRect()

query.exec((res) => {
//res会是null
});