js渐入渐出效果没有

有没有哪位跟着老师的步骤走但是没有渐入渐出效果的？而是直接就跳出来的？汇报addH not defined的错
 <script>
        window.onload=function(){
            var Lis=document.getElementsByTagName('li');
           for(var i=0;i<Lis.length;i++){
               Lis[i].onmouseover=function(){
                   var u=this.getElementsByTagName('ul')[0];
                  // console.log(u);
                   if(u != undefined){
                       u.style.display=' block';
                       addH(u.id);
                   }
                   Lis[i].onmouseleave=function(){
                        var u=this.getElementsByTagName('ul')[0];
                        if(u != undefined){
                            u.style.display='none';
                            subH(u.id);
                        }
               }
               }
           }

            function addH(id){
                var ulList=document.getElementById(id);
                var h=ulList.offsetHeight;
                h+=1;
                if(h <= 42){
                    ulList.style.height=h+'px';
                    setTimeout(addH('"+id+"'),10);
                    debugger;
                    /* debugger;
                     addH(id);*/
                }
                else{
                    return;
                }
            }
            function subH(id){
                var ulList=document.getElementById(id);
                var h=ulList.offsetHeight;
                h-=1;
                if(h > 0){
                    ulList.style.height=h+'px';
                    setTimeout(subH('"+id+"'),10);
                }
            }
        }

    </script>
</head>
<body>
    <!-- 代码 开始 -->
    <div id="menu">
        <ul id="nav">
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            </li>
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            <li class="mainlevel"><a href="#">关于我们</a></li>
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盏中柳色浅
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js渐入渐出效果没有

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