function checkNum(object) {
 var checkOK = "0123456789-";
 var checkStr = object.value;
 var decPoints = 0;
 var allNum = "";
 for (i = 0; i < checkStr.length; i++) {
  ch = checkStr.charAt(i);
  for (j = 0; j < checkOK.length; j++) {
   if (ch == checkOK.charAt(j)) break;
   if (j == checkOK.length) return false;
  }
 }
 return true;
}