js 文件名截取（后缀名、全名、不带后缀名）

<script language="javascript"type="text/javascript">
 

      //取整个文件的路径并且把文件名赋给文件名
       var isTrue = true;
       function GetName(obj) {
           CheckType(obj);

           if (isTrue) {
               //隐藏控件赋值

               var hfExName =document.getElementByIdx_x("<%=hfExName.ClientID%>");
               hfExName.value = GetFileName(obj.value);
              //服务控件文本框jq写法    id=   "txtName"  <Asp:TextBox/>        

              $("#<%=txtName.ClientID%> input")[0].value =GetFileNameNoExt(obj.value);  //GetFileName(obj.value);
           }
       }
       //字符串逆转
       function strturn(str) {
           if (str != "") {
           var str1 = "";
           for (var i = str.length - 1; i >= 0; i--) {
               str1 += str.charAt(i);
           }
           return (str1);
           }
       }
       //限制文件类型
       function CheckType(obj) {

           if (obj.value.length > 0) {
               var af ="txt,docx,doc,docm,dotx,dotm,pptx,accdb,vsd,xlsx,xlsm,xltx,xlsb,xlam";
               if (eval_r("with(obj.value)if(!/" + af.split(",").join("|") +"/ig.test(substring(lastIndexOf('.')+1,length)))1;")) {
                   alert("支持上传文件类型：\n" + af);

                   isTrue = false;
               } else {
                   isTrue = true;

               }
           } else {

               isTrue = false;
           }
       }
       //取文件后缀名
       function GetFileExt(filepath) {
           if (filepath != "") {
               var pos = "." + filepath.replace(/.+\./, "");
               return pos;
           }
       }
       //取文件名不带后缀
       function GetFileNameNoExt(filepath) {
           var pos = strturn(GetFileExt(filepath));
           var file = strturn(filepath);
           var pos1 =strturn( file.replace(pos, ""));
           var pos2 = GetFileName(pos1);
           return pos2;

       }
       //取文件全名名称
       function GetFileName(filepath) {
           if (filepath != "") {
               var names = filepath.split("\\");
               return names[names.length - 1];
           }
       }
       //动态绑定文件详细类型
       function DataBind(e, s) {
           $.ajax({
               type: "POST",
               processData: false, //用POST方式传输
               url:'../AjaxRequestPages/SellContract/Ajax_SellPactFileManager.aspx?FileTypeID='+ s.GetValue(), //目标地址
               success: SetDdlFPType
           });
           //               success: function(json));
       }
       //回调函数
       function SetDdlFPType(htmls) {
           if (htmls != null && htmls != ""){
               var l = htmls.length;