<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;}