jquery - 粘性标题滚动问题

Question

我在网站上有一个粘性 header 。但是当视口(viewport)底部下方有非常特定数量的内容时(大约等于我的 html 上的 2-3x padding-top)，如果尝试缓慢滚动，滚动会上下振荡。如果页面下方有大量内容，则效果很好。

编辑: 抱歉，如果我原来的问题不够清楚，但我希望整个页面滚动直到“标题”到达屏幕顶部，然后(并且只有在那时)让标题停止滚动，而页面的其余内容继续滚动在它后面滚动。

这是一个 JSfiddle

$(function () {
    // Check the initial Poistion of the Sticky Header
    var stickyHeaderTop = $('#stickyheader').offset().top;

    $(window).scroll(function () {
        if ($(window).scrollTop() > stickyHeaderTop) {
            $('#stickyheader').css({
                position: 'fixed',
                top: '0px'
            });
            $('#othercontent').css('margin-top', $('#stickyheader').outerHeight(true));
        } else {
            $('#stickyheader').css({
                position: 'static',
                top: '0px'
            });
            $('#othercontent').css('margin-top', '0px');
        }
    });
});

body {
    font: 13px sans-serif;
    padding-top: 20px;
}
#stickyheader {
    width: 100%;
    height: 40px;
    background:black;
    color:white;
    margin-bottom: 10px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="stickyheader">Sticky header</div>
<div id="othercontent">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.</p>
</div>

Answer 1

您正在检查 if ($(window).scrollTop() > stickyHeaderTop)，它允许标题在运行您的代码以更新 CSS 之前在屏幕上方向上滚动一个像素，然后CSS 将其向下推。

此外，您正在根据正在修改的元素运行计算，从而导致抖动。首先设置计算出的边距，然后对 #stickyheader 元素执行编辑:

$(function () {
    var stickyHeaderTop = $('#stickyheader').offset().top;

    $(window).scroll(function () {
        if ($(window).scrollTop() >= stickyHeaderTop) { // <-- Notice the greater than or equals to.
            $('#othercontent').css('margin-top', $('#stickyheader').outerHeight(true)); // <-- This has to be before the #stickyheader changes.
            $('#stickyheader').css({
                position: 'fixed',
                top: '0px'
            });
        } else {
            $('#stickyheader').css({
                position: 'static',
                top: '0px'
            });
            $('#othercontent').css('margin-top', '0px');
        }
    });
});

$(function () {
    var stickyHeaderTop = $('#stickyheader').offset().top;

    $(window).scroll(function () {
        if ($(window).scrollTop() >= stickyHeaderTop) {
            $('#othercontent').css('margin-top', $('#stickyheader').outerHeight(true));
            $('#stickyheader').css({
                position: 'fixed',
                top: '0px'
            });
        } else {
            $('#stickyheader').css({
                position: 'static',
                top: '0px'
            });
            $('#othercontent').css('margin-top', '0px');
        }
    });
});

body {
    font: 13px sans-serif;
    padding-top: 20px;
}
#stickyheader {
    width: 100%;
    height: 40px;
    background:black;
    color:white;
    margin-bottom: 10px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="stickyheader">Sticky header</div>
<div id="othercontent">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.</p>
</div>