function ISO8601Z(date) {
     // handles years from 0000 to 9999 only
     return ("000" + date.getUTCFullYear()).slice(-4) +
       "-" + ("0" + (date.getUTCMonth() + 1)).slice(-2) +
       "-" + ("0" + date.getUTCDate()).slice(-2) +
       "T" + ("0" + date.getUTCHours()).slice(-2) +
       ":" + ("0" + date.getUTCMinutes()).slice(-2) +
       ":" + ("0" + date.getUTCSeconds()).slice(-2) +
       "," + ("00" + date.getUTCMilliseconds()).slice(-3) +
       "Z";
   }
   function ISO8601Local(date) {
     // handles years from 0000 to 9999 only
     var offset = date.getTimezoneOffset();
     var offsetSign = "-";
     if (offset <= 0) {
       offsetSign = "+";
       offset = -offset;
     }
     var offsetHours = Math.floor(offset / 60);
     var offsetMinutes = offset - offsetHours * 60;
     return ("000" + date.getFullYear()).slice(-4) +
       "-" + ("0" + (date.getMonth() + 1)).slice(-2) +
       "-" + ("0" + date.getDate()).slice(-2) +
       "T" + ("0" + date.getHours()).slice(-2) +
       ":" + ("0" + date.getMinutes()).slice(-2) +
       ":" + ("0" + date.getSeconds()).slice(-2) +
       "," + ("00" + date.getMilliseconds()).slice(-3) +
       offsetSign + ("0" + offsetHours).slice(-2) +
       ":" + ("0" + offsetMinutes).slice(-2);
   }

   var now = new Date();
   document.writeln("<p>UTC client time is ", ISO8601Z(now), "</p>");
   document.writeln("<p>Local client time is ", ISO8601Local(now), "</p>");