function IsNumeric(strString)   //  check for valid numeric strings	  
 {
    var strValidChars = "0123456789";
    var strChar;
       var blnResult = true;
          if (strString.length == 0) return false;   //  test strString consists of valid characters listed above   
          for (i = 0; i < strString.length && blnResult == true; i++)  
              {   
                 strChar = strString.charAt(i);   
                    if (strValidChars.indexOf(strChar) == -1)   
                          {   
                                blnResult = false;     
                                    }
                                          }
                                             return blnResult; 
                                               }