导航跟随滚动条置顶移动示例代码_javascript技巧

jQuery(document).ready(function() {
var topmenu = jQuery("#topmenu");
var topmenu_top = topmenu.offset().top;
reset_topmenu_top(topmenu, topmenu_top);
jQuery(window).scroll(function() {
reset_topmenu_top(topmenu, topmenu_top);
});
});
function reset_topmenu_top(topmenu, topmenu_top) {
var document_scroll_top = jQuery(document).scrollTop();
if (document_scroll_top > topmenu_top) {
topmenu.css('top', document_scroll_top);
}
if (document_scroll_top <= topmenu_top) {
topmenu.css('top', topmenu_top);
}
}


效果图如下：