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<title>监视滚动像素，显示或隐藏顶部导航条-柯乐义</title>
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<div style="background-color:#959822; width:100%;height:150px;">请滚动鼠标使页面向下</div>
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<div style="background-color:Olive; width:100%;height:150px;">柯乐义 监视下滚像素</div>
<div style="background-color:Green; width:100%;height:150px;">A</div>
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<div style="background-color:Orange; width:100%;height:150px;">完整代码</div>
<script type="text/javascript">
$(function () {
//当滚动条的位置处于距顶部200像素以下时，顶部导航出现，否则消失
$(function () {
$(window).scroll(function () {
if ($(window).scrollTop() > 200) {
$("#topmenu_keleyi_com").fadeIn(100);
}
else {
$("#topmenu_keleyi_com").fadeOut(100);
}
});
});
});
</script>
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