表单js验证文件上传大小

"-//W3C//DTD HTML 4.01 Transitional//EN"  "http://www.w3.org/TR/html4/loose.dtd" >

  "Content-Type"  content= "text/html; charset=windows-31j" >

  Insert title here
  "text/javascript" >

     var  isIE = /msie/i.test(navigator.userAgent) && !window.opera;

     var  sizeLabel = [ "B" ,  "KB" ,  "MB" ,  "GB" ];

     function  fileChange(target) {

         var  fileSize = 0;

         if  (isIE && !target.files) {
             var  filePath = target.value;
             var  fileSystem =  new  ActiveXObject( "Scripting.FileSystemObject" );
             var  file = fileSystem.GetFile (filePath);
             fileSize = file.Size;
         }  else  {
             fileSize = target.files[0].size;
         }
         displayFileSize(fileSize);
     }

     function  displayFileSize(size) {
         var  fileSize = document.getElementById( "fileSize" );
         fileSize.innerHTML = calFileSize(size);
     }

     function  calFileSize(size) {
         for  ( var  index = 0; index  < sizeLabel.length; index++) {

             if  (size  < 1024) {
                 return  round(size, 2) + sizeLabel[index];
             }

             size = size / 1024;
         }

         return  round(size, 2) + sizeLabel[index];
     }

     function  round(number, count) {
         return  Math.round(number * Math.pow(10, count)) / Math.pow(10, count);
     }

      

 

          "file"  onchange= "fileChange(this);" >

 

      "fileSize" >