学习链接：蒙层禁止页面滚动的方案
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<head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1"><title>蒙层禁止页面滚动的方案</title><style type="text/css">#mask{position: fixed;height: 100vh;width: 100vw;background: rgba(0, 0, 0, 0.6);top: 0;left: 0;display: flex;align-items: center;justify-content: center;}.hide{display: none !important;}.long-content > div{height: 300px;}.mask-content{width: 300px;height: 100px;overflow-x: auto;background: #fff;}.mask-content > div{height: 300px;}</style>
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<body><div class="long-content"><div>long content</div><div>long content</div><div>long content</div><button id="btn">弹窗</button><div>long content</div><div>long content</div><div>long content</div><div>long content</div></div><div id="mask" class="hide"><div class="mask-content"><div>mask-content</div><div>mask-content</div><div>mask-content</div><div>mask-content</div><div>mask-content</div><div>mask-content</div><div>mask-content</div><div>mask-content</div><div>mask-content</div></div></div>
</body><script type="text/javascript">(() => {const btn = document.getElementById("btn");const mask = document.getElementById("mask");const maskContent = document.querySelector(".mask-content");const body = document.body;let documentTop = 0; // 记录按下按钮时的 `top`/* 按钮点击时: 1. 给mask添加display:none; 2. 记录此时页面被卷去的高度(记录滚动位置)3. 给body加上fixed固定定位（此时，如果不做任何处理，页面会立即滚动到top:0的位置）; 4. 将页面滚动到之前记录的位置（恢复弹窗前的位置）*/btn.addEventListener("click", e => {mask.classList.remove("hide");documentTop = document.scrollingElement.scrollTop;body.style.position = "fixed"body.style.top = -documentTop + "px";})/* 点击蒙层时: 1. 给mask添加hide样式类, 让mask的display为none2. 恢复body的默认定位（此时，如果不做任何处理，页面又会立即滚动到top:0的位置）3. 将页面滚动到之前记录的位置（恢复弹窗前的位置）*/mask.addEventListener("click", e => {mask.classList.add("hide");body.style.position = "static";body.style.top = "auto";document.scrollingElement.scrollTop = documentTop;})/* 阻止事件冒泡, 防止点击弹框中的内容时, 也把弹框关闭了 */maskContent.addEventListener('click',(e) => {e.stopPropagation();})})();</script>
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