vue3中使用@vueuse/core中的图片懒加载案例详解

npm i @vueuse/core

import { useIntersectionObserver } from '@vueuse/core'
import {ref} from "vue";

export const useLazyData = (apiFn) => {
    const result = ref([])
    const target = ref(null)
    // stop 停止观察
    const { stop } = useIntersectionObserver(
        // 监听的目标元素
        target,
        ([{ isIntersecting }], observerElement) => {
            // isIntersecting 是否进入可视区
            if (isIntersecting) {
                stop()
                // 调用API函数获取数据
                 const aa  = apiFn()
                console.log('aa', aa)
                result.value = aa
                // // 调用API函数获取数据  
		        // apiFn().then(data => {
		        //   result.value = data.result
		        // })
            }
        },
        // 配置选项，相交的比例大于0就触发
        {
            threshold: 0
        }
    )
    return { result, target }
}

<template>
<div>
  <div class="up"></div>
  <div ref="target" :style="{backgroundColor: bgc}" class="down"></div>
</div>
</template>

<script setup>
import {useLazyData} from "@/helloworld";
import {nextTick, onMounted, ref} from "vue";
let bgc = ref('#000')

// 发送请求的函数
// export const findNew = () => {
//    return request('/home/new', 'get')
// }
const qingqiuhanshu = () => {
  // 模仿请求
  return '#1DC779'
}
const { target, result } = useLazyData(qingqiuhanshu)
bgc = result

</script>

<style lang="less" scoped>
.up{
  height: 100vh;
  margin-bottom: 20px;
  background-color: pink;
}
.down{
  height: 50px;
  background-color: deeppink;
}
</style>