js实现鼠标移入移出卡片切换内容

<div class="sports-purple">   <div class="all">        <!-- 内容 -->    <div class="content">          <div class="first-block">      <!-- 内容的侧边栏 -->      <div class="aside">       <h2>Categories</h2>       <ul class="lis">        <li class="sna">         <a href="#">Sneakers</a>         <div id="sub">           <div><a href="#">Running Shoes</a></div>           <div><a href="#">Basketball Shoes</a></div>           <div><a href="#">Soccer Shoes</a></div>           <div><a href="#">Hiking Shoes</a></div>           <div><a href="#">Skateboarding Shoes</a></div>           <div><a href="#">Dance shoes</a></div>           <div><a href="#">Tennis Shoes</a></div>           <div><a href="#">Cycling Shoes</a></div>           <div><a href="#">Walking Shoes</a></div>           <div><a href="#">Golf Shoes</a></div>         </div>        </li>        <li class="sna">         <a href="#">Sports Clothing</a>         <div id="sup">           <div><a href="#">Jackets</a></div>           <div><a href="#">Base Layers</a></div>           <div><a href="#">Shirts</a></div>           <div><a href="#">Sets/Suits</a></div>         </div>        </li>        <li class="sna">         <a href="#">Cycling</a>         <div id="cyc">           <div><a href="#">Bicycle</a></div>           <div><a href="#">Bicycle Parts</a></div>           <div><a href="#">Bicycle Accessories</a></div>           <div><a href="#">Bicycle Repair Tools</a></div>           <div><a href="#">Cycling Clothings</a></div>           <div><a href="#">Cycling Shoes</a></div>           <div><a href="#">Electric Bicycle</a></div>           <div><a href="#">Electric Bicycle Part</a></div>           <div><a href="#">Self Balance Scooters</a></div>         </div>        </li>        <li class="sna">         <a href="#">Finshing</a>         <div id="fin">           <div><a href="#">Fishing Rods</a></div>           <div><a href="#">Fishing Reels</a></div>           <div><a href="#">Rod Combo</a></div>           <div><a href="#">Fishing Lures</a></div>           <div><a href="#">Fishing Lines</a></div>           <div><a href="#">Fishhooks</a></div>           <div><a href="#">Fishing Tackle Boxes</a></div>           <div><a href="#">Fishing Float</a></div>           <div><a href="#">Fishing Net</a></div>           <div><a href="#">Fishing Rope</a></div>         </div>        </li>        <li class="sna">         <a href="#">Hunting</a>         <div id="hun">           <div><a href="#">Bow & Arrow</a></div>           <div><a href="#">Hunting Optics</a></div>           <div><a href="#">Hunting Cameras</a></div>           <div><a href="#">Weapon Lights</a></div>           <div><a href="#">Hunting Bags & Holsters</a></div>           <div><a href="#">Hunting Knife</a></div>           <div><a href="#">Hunting Lights</a></div>           <div><a href="#">Hunting Decoy</a></div>           <div><a href="#">Hunting Gun Accessories</a></div>           <div><a href="#">Scope Mounts & Accessories</a></div>         </div>        </li>        <li class="sna">         <a href="#">Camping & Hiking</a>         <div id="cam">           <div><a href="#">Tents</a></div>           <div><a href="#">Sun Shelter</a></div>           <div><a href="#">Sleeping Bags</a></div>           <div><a href="#">Climbing Bags</a></div>           <div><a href="#">Outdoor Stoves</a></div>           <div><a href="#">Outdoor Tablewares</a></div>           <div><a href="#">Picnic Bags</a></div>           <div><a href="#">Water Bags</a></div>           <div><a href="#">Camping Mat</a></div>           <div><a href="#">Outdoor Lighting</a></div>         </div>        </li>        <li class="sna">         <a href="#">Fitness & Body Building</a>         <div id="fit">           <div><a href="#">Fitness Equipments</a></div>           <div><a href="#">Outdoor Fitness Equipment</a></div>           <div><a href="#">Boxing</a></div>           <div><a href="#">Yoga</a></div>           <div><a href="#">Gymnastics</a></div>           <div><a href="#">Martial Arts</a></div>           <div><a href="#">Weight Lifting</a></div>           <div><a href="#">Weight Lifting Gloves</a></div>           <div><a href="#">Fitness Gloves</a></div>           <div><a href="#">Dance shoes</a></div>         </div>        </li>        <li class="sna">         <a href="#">Musical Instruments</a>         <div id="mus">           <div><a href="#">Guitar</a></div>           <div><a href="#">Guitar Parts & Accessories</a></div>           <div><a href="#">Violin</a></div>           <div><a href="#">Violin Parts & Accessories</a></div>           <div><a href="#">Woodwind Instruments</a></div>           <div><a href="#">Percussion Instruments</a></div>           <div><a href="#">Instrument Bags & Cases</a></div>           <div><a href="#">Brass Instruments</a></div>           <div><a href="#">Keyboard Instruments</a></div>         </div>        </li>       </ul>              <div class="flip">        <a href="#"class="page pagedown">         <img src="../images/arrow.png">        </a>        <a href="#"class="page pageup">         <img src="../images/arrow.png">        </a>        <div class="tail">         1/3        </div>       </div>      </div>           </div>      </div>    </div>   </div> </div>

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// 根据类名获取livar lis = document.getElementsByClassName("sna"); //循环遍历类名为sna的li标签for(var i = 0;i<lis.length;i++){ //为li注册鼠标移入事件 lis[i].onmouseover = function(){  /* this：类名为sna的li */  //console.log(this);  /* this.children：获取的li标签下的子元素 */  // console.log(this.children);  var next  = this.children;  //next[1]:在li下的两个子元素中，需要显示出来的元素的标签的下标为1  next[1].style.display = "block"; }; //为li注册鼠标移出事件 lis[i].onmouseout = function(){  var next  = this.children;  next[1].style.display = "none"; };}