jQuery实现固定顶部 定位滚动导航效果代码，很常见的效果，非常实用；滚动滚动条时，导航固定顶部，并且滚动到对应的板块时，当前导航高亮显示；点击导航文字时平滑跳转到对应的板块。
$(function(){
var subNav_active = $(".adv_active");
var subNav_scroll = function(target){
subNav_active.removeClass ("adv_active");
target.parent().addClass("adv_active");
subNav_active = target.parent();
};
$("#subNav a").click(function(){
subNav_scroll($(this));
var target = $(this).attr("href");
var targetScroll = $(target).offset().top - 80;
$("html,body").animate({scrollTop:targetScroll},300);
return false;
});
//页面跳转时定位
if(window.location.hash){
var targetScroll = $(window.location.hash).offset().top - 80;
$("html,body").animate({scrollTop:targetScroll},300);
}
$(window).scroll(function(){
var $this = $(this);
var targetTop = $(this).scrollTop();
var footerTop = $("#footer").offset().top;
var height = $(window).height();
if (targetTop >= 520){
$("#subNav").addClass("fixedSubNav");
$(".empty-placeholder").removeClass("hidden");
}else{
$("#subNav").removeClass("fixedSubNav");
$(".empty-placeholder").addClass("hidden");
}
if(targetTop < 750){
subNav_scroll($(".adv_door"));
}else if(targetTop > 1200 && targetTop < 1640){
subNav_scroll($(".adv_source"));
}else if(targetTop > 2314 && targetTop < 2734){
subNav_scroll($(".adv_price"));
}else if(targetTop > 2968 && targetTop < 3268){
subNav_scroll($(".adv_transfer"));
}else if(targetTop > 3327 && targetTop < 3627){
subNav_scroll($(".adv_payment"));
}else if(targetTop > 3651 && targetTop < 4071){
subNav_scroll($(".adv_promise"));
}else if(targetTop > 4163 && targetTop < 4473){
subNav_scroll($(".adv_ride"));
}else if(targetTop > 4580){
subNav_scroll($(".adv_finance"));
}
})
}());