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滚动条相关事件

2022-01-21 15:06:10 作者：互联网

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div,p{
            margin: 0;
            padding: 0;
        }
        #content {
            background-color: orange;
            height: 4000px;
            width: 100%;
            display: flex;
            flex-direction: column;
            justify-content: space-between;
        }

        #backTop {
            position: fixed;
            top: 20px;
        }

        #backBottom {
            position: fixed;
            bottom: 20px;
        }

        .arrow {
            width: 100px;
            padding: 10px;
            right: 20px;
            background-color: antiquewhite;
            border-radius: 5px;
            text-align: center;
            display: none;
        }
        .box{
            background-color: aqua;
            width: 100%;
            line-height: 40;
        }
    </style>
</head>

<body>
    <div id="content">
        <p class="box">我是顶部</p>
        <p class="box">我是底部</p>
    </div>
    <div id="backTop" class="arrow">回到顶部</div>
    <div id="backBottom" class="arrow">到达底部</div>
    <script>
        window.onload = function () {
            let content = document.getElementById("content");
            let backBottom = document.getElementById("backBottom");
            let backTop = document.getElementById("backTop");

            let currentScrollTop = document.documentElement.scrollTop;

            window.onscroll = function (e) {
                if (document.documentElement.scrollTop > currentScrollTop) {
                    backTop.style.display = "none";
                    backBottom.style.display = "block";
                    currentScrollTop = document.documentElement.scrollTop;
                } else {
                    backTop.style.display = "block";
                    backBottom.style.display = "none";
                    currentScrollTop = document.documentElement.scrollTop;
                }
            }
            backTop.onclick = function(){
                document.documentElement.scrollTop = 0;
            }
            backBottom.onclick = function(){
                document.documentElement.scrollTop = content.clientHeight;
            }
        }
    </script>
</body>

</html>

标签：documentElement,滚动条,backTop,事件,backBottom,scrollTop,相关,document,display
来源： https://blog.csdn.net/weixin_39739671/article/details/122621653