<input name="" type="text"  id="newDirtxt"/> <input class="btn" name="" type="button" value="创建新目录"  onclick="newDir()" />   ?<BR><BR><BR>Js代码 <BR><BR><script type="text/javascript"> ////创建新目录         function newDir() {             var txt = document.getElementById("newDirtxt");             var dirname = txt.value;             if (dirname) {                 alert("请填写目录名");             } else {                 $.ajax({                     type: "Post",                     url: "/center/directorynew",                     async: false,                     data: { dirname: dirname },                     success: function(msg) {                         if (msg.length < 40) {                             var DirectoryID = document.getElementById("DirectoryID");                             var tOption = document.createElement("Option");                             tOption.text = dirname;                             tOption.value = msg;                             DirectoryID.appendChild(tOption);                             txt.value = "";                             alert("增加成功");                         } else {                             alert("增加失败");                         }                     }                 });             }//else         }     </script><BR><BR><BR>后台代码 <BR><BR>返回刚刚插入的目录的id字符串 <BR>