javascript - 粘性导航栏在 Firefox 中消失

Question

我最近使用以下代码向我网站的导航栏添加了“粘性”功能:

<nav>
    <div class="menu-navigation-container">
        <ul class="menu" id="menu-navigation">
            <li class="menu-item" id="menu-item-50"><a href="#">BlahBlah</a></li>
            <li class="menu-item" id="menu-item-51"><a href="#">BlahBlah</a></li>
            <li class="menu-item" id="menu-item-49"><a href="#">BlahBlah</a></li>
            <li class="menu-item" id="menu-item-48"><a href="#">BlahBlah</a></li>
            <li class="menu-item" id="menu-item-47"><a href="#">BlahBlah</a></li>
        </ul>
    </div>            
</nav>

负责棍子的 JavaScript:

$(document).ready(function () {
    var header = $('nav').position().top;
    var navHeight = $('nav').outerHeight();

    $(window).scroll(function () {
        var windowpos = $(window).scrollTop();

        if(windowpos > header) {
                $('nav').addClass('fixed').css('top', '0').next().css('margin-top', navHeight + 'px');
            }
            else {
                $('nav').removeClass('fixed').next().css('margin-top', '0');
            }
    });
});

还有 .sticky CSS 类:

.fixed {
    -webkit-box-shadow: 0 4px 10px -3px #000;
    -moz-box-shadow: 0 4px 10px -3px #000;
    -o-box-shadow: 0 4px 10px -3px #000;
    box-shadow: 0 4px 10px -3px #000;
    position: fixed !important;
}

它在 Chrome、Safari 和 IE 上工作得很好，但由于某种原因，导航栏在到达 Firefox 窗口顶部时完全消失了。有什么想法吗？

Answer 1

我的示例是否也发生了同样的情况？如果是这样，我们就能查个水落石出。

代码 + JSFiddle

http://jsfiddle.net/fbfWG/

HTML

<nav>
    <div class="menu-navigation-container">
        <ul class="menu" id="menu-navigation">
            <li class="menu-item" id="menu-item-50"><a href="#">BlahBlah</a>

            </li>
            <li class="menu-item" id="menu-item-51"><a href="#">BlahBlah</a>

            </li>
            <li class="menu-item" id="menu-item-49"><a href="#">BlahBlah</a>

            </li>
            <li class="menu-item" id="menu-item-48"><a href="#">BlahBlah</a>

            </li>
            <li class="menu-item" id="menu-item-47"><a href="#">BlahBlah</a>

            </li>
        </ul>
    </div>
</nav>

CSS

body {
    height:2000px;
    margin:100px 0 0 0;
    padding:0;
}
nav {
    padding:10px;
    background:red;
    width:100%;
}
a {
    text-decoration:none;
}
ul {
    margin:0;
    padding:0;
    list-style-type:none;
}
ul li {
    display:inline-block;
    margin-right:10px;
}
.fixed {
    position: fixed;
    top:0;
    left:0;
    width:100%;
}
/* apply a natural box layout model to all elements */
 *, *:before, *:after {
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}

JS

$(document).ready(function () {
    var header = $('nav').offset().top;
    var navHeight = $('nav').outerHeight();

    $(window).scroll(function () {
        var windowpos = $(window).scrollTop();

        if (windowpos > header) {
            $('nav').addClass('fixed').next().css('margin-top', navHeight + 'px');
        } else {
            $('nav').removeClass('fixed').next().css('margin-top', '0');
        }
    });

});