Calculation of DST in Javascript -

i using below code calculate different countries manually not reflecting dst kindly guide me achive same st gallen time 1 hour back.

<span id="clock01"></span> <script type="text/javascript"> function calctime00(city, offset) { settimeout("1");     d5 = new date();     d = new date();     utc = d.gettime() + (d.gettimezoneoffset() * 60000);       nd = new date(utc + (3600000*offset));//by smt     var area=""+city+"&nbsp&nbsp&nbsp&nbsp&nbsp"+nd.tolocaletimestring().replace(/:\d{2}\s/,'  ');     $('#clock01').html(area);      settimeout(function () { calctime00('','+2');}, 1000);     } </script>