jQuery floating navigation menu suitable for shopping product type websites_jquery

A single-page web page has a lot of content and the page length is large. It needs to be conveniently and quickly positioned at different locations on the page, so floating menus have gradually become popular, as shown below for men's clothing, women's clothing, beauty, etc.

This menu function is divided into two parts:

1. Click on the menu item and the web page will scroll to the corresponding position. This can be achieved simply through anchor points;

2. When scrolling the page, the selected status of the menu item needs to change accordingly. This requires monitoring the scrolling event of the web page and implementing it through a little calculation;

Calculate the size relationship between scrollTop and the offsetTop of each div, determine where the current web page is displayed, and then add styles to the corresponding menu items based on the calculated results. For example, the offset().top of the second div = 300, the offset().top of the third div = 600, and the scrollTop at this time = 400, indicating that most of the displayed position is the position of the second div, and 700 is the third div. Here is a simple example:

<div id="menu">
<ul>
<li><a href="#item1" class="current">1F 男装</a></li>
<li><a href="#item2">2F 女装</a></li>
<li><a href="#item3">3F 美妆</a></li>
<li><a href="#item4">4F 数码</a></li>
<li><a href="#item5">5F 母婴</a></li>
</ul>
</div>
<div id="content">
<h1 id="网购">网购</h1>

<div id="item1" class="item">
<h2 id="F-男装">1F 男装</h2>
<ul>
<li><a href="#"><img src="" alt=""/></a></li>
<!-- 若干个li -->
</ul>
</div>
<!-- 若干个item-->
</div>

* {margin: 0;padding: 0;}
body {font-size: 12px;line-height: 1.7;}
li {list-style: none;}
#content {width: 800px;margin: 0 auto;padding: 20px;}
#content h1 {color: #0088bb;}
#content .item {padding: 20px;margin-bottom: 20px;border: 1px dotted #0088bb;}
#content .item h2 {font-size: 16px;font-weight: bold;border-bottom: 2px solid #0088bb;margin-bottom: 10px;}
#content .item li {display: inline;margin-right: 10px;}
#content .item li a img {width: 230px;height: 230px;border: none;}
#menu{position:fixed;left:50%;margin-left:400px;top:100px;}
#menu ul li a {
display: block;
margin: 5px 0;
font-size: 14px;
font-weight: bold;
color: #333;
width: 80px;
height: 50px;
line-height: 50px;
text-decoration: none;
text-align: center;
}
#menu ul li a:hover,#menu ul li a.current {color: #fff;background: #0088bb;}

$(function(){
$(window).scroll(function(){
var scrollTop = $(document).scrollTop();
var contentItems = $("#content").find(".item");
var currentItem = "";
contentItems.each(function(){
var contentItem = $(this);
var offsetTop = contentItem.offset().top;
if(scrollTop > offsetTop-200){//此处的200视具体情况自行设定，因为如果不减去一个数值，在刚好滚动到一个div的边缘时，菜单的选中状态会出错，比如，页面刚好滚动到第一个div的底部的时候，页面已经显示出第二个div，而菜单中还是第一个选项处于选中状态
currentItem = "#" + contentItem.attr("id");
} 
});
if(currentItem&&currentItem!=$("#menu").find(".current").attr("href")){
$("#menu").find(".current").removeClass("current");
$("#menu").find("[href=" + currentItem + "]").addClass("current");
}
});
});