Numeric Validation

<script type="text/javascript">
     function NumericValidation(eventObj) {
         var keycode;

         if (eventObj.keyCode) //For IE
             keycode = eventObj.keyCode;
         else if (eventObj.Which)
             keycode = eventObj.Which;  // For FireFox
         else
             keycode = eventObj.charCode; // Other Browser

         if (keycode != 8) //if the key is the backspace key
         {
             if (keycode < 48 || keycode > 57) //if not a number
                 return false; // disable key press
             else
                 return true; // enable key press
         }
     }
    </script>