js addEventListener监听scroll滚动条 距离底部一定距离 加载数据 超过最大高度移除监听事件

//测试dmeon.testBox{height: 450px;border: 1px solid rebeccapurple;width: 500px;color: blueviolet;overflow-y: auto;}

在这里插入代码片```<div class="testBox"><div class="sunBox"><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div><div class="childBox">今天天气不错</div></div></div>```javascript<script>let sumH ="";function scrollH(){let testBox = document.getElementsByClassName("testBox");let sunBox = document.querySelector(".sunBox");let appendDiv = document.createElement("div");appendDiv.innerText = "我在追加";console.log(testBox[0].scrollTop,"scrollTop");//滚动条距离顶部高度console.log(testBox[0].scrollHeight,"scrollHeight");//整个内容的高度包括隐藏的内容console.log(testBox[0].offsetHeight,"offsetHeight");//盒子的高度sumH = testBox[0].offsetHeight + testBox[0].scrollTop;if(sumH <=1100 && sumH+50>testBox[0].scrollHeight){sunBox.appendChild(appendDiv)}if(sumH>1000){window.removeEventListener("scroll", scrollH,true); //监听滚动事件}console.log(sumH,"sumH")}window.addEventListener("scroll", scrollH,true); //监听滚动事件</script>