<div class="ph-nav" data-pdt-block="pheader-n">
 <div class="ph-nav_shadow" style="left: 0px; width: 62px;"></div>
 <ul>
 <li class="ph-nav_item ph-nav_item--current">
 <a href="/" rel="external nofollow" >
 首頁
 
 </a>
 </li>
 <li class="ph-nav_item">
 <a href="/all" rel="external nofollow" >
 全部
 </a>
 </li>
 ...
 </ul>
</div>

 <header>
 <div class="w">
 <div class="header_logo l"><img src="img/logo.png" alt=""></div>
 <div class="header_nav r">
 <div class="header_nav_shadow"></div>
 <ul>
 <li class="header_nav_li-hover"><a href="">首頁</a></li>
 <li><a href="">智能家居</a></li>
 <li><a href="">案例展示</a></li>
 <li><a href="">致創(chuàng)能源</a></li>
 <li><a href="">答疑解惑</a></li>
 <li><a href="">合作加盟</a></li> 
 </ul>
 </div>
 </div> 
 </header>

.header_nav{
 width: 592px;
 height: 50px;
 position: relative;
}
.header_nav_shadow{
 position: absolute;
 top: 0;
 left: 0;
 bottom: 0;
 width: 72px;
 background: #F29400;
 transition: all ease-in-out .3s;
 z-index: 1;
}
.header_nav ul li{
 display: block;
 float: left;
 overflow: hidden;
 height: 50px;
 line-height: 50px;
 transition: all ease-in-out .3s;
 position: relative;
 z-index: 2;
}
.header_nav_li-hover a{
 color: #fff;
}
.header_nav ul li a{
 display: block;
 padding: 0 20px;
 height: 50px;
 line-height: 50px;
 transition: all ease-in-out .3s;
}

$(document).ready(function() { 
 $(".header_nav ul li").hover(function() { 

 var change = getLiData($(this));
 $(".header_nav_shadow").css('left',change[0]).width(change[1]);
 $(".header_nav ul").children("li:first-child").removeClass("header_nav_li-hover"); 
 $(this).addClass("header_nav_li-hover"); 
 }, function() { 
 $(".header_nav_shadow").css('left',0).width('72');
 $(this).removeClass("header_nav_li-hover"); 
 $(".header_nav ul").children("li:first-child").addClass("header_nav_li-hover");
 }); 
});
// 根據(jù)this li 獲取需要改變的長度和偏移量
function getLiData(li){
 var left = 0;
 for(let i=0;i<li.index();i++){
 left+=$(".header_nav ul li:eq("+i+")").width();
 }
 var change=[left,li.width()];
 return change;
}