js中获取首屏的宽高和滚动距离监听

作者: SmallTwo | 来源:发表于2017-04-18 13:38 被阅读126次

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        #content{
            width: 100%;
            height: 2000px;
            background: -webkit-gradient(linear,0 0, 0 1500,from(yellow),to(blue));
        }
        #btn {
            display: none;
            position: fixed;
            right: 100px;
            bottom: 100px;
        }
    </style>
</head>
<body>

<div id="content">
    <input type="button" value="点击" id="btn">
</div>
<script>
    var btn = document.getElementById('btn'),content = document.getElementById('content');
    window.onscroll = function () {
        // 获取窗口滚动的距离
        var scrolDis = document.documentElement.scrollTop || document.body.scrollTop;
        // 获取首屏窗口的高度
        var firHei = document.documentElement.clientHeight || document.body.clientHeight;

       btn.style.display =  scrolDis > firHei ? 'block' : 'none';
    };
</script>
</body>
</html>