function getOffset() {//get client timezone offset.
       var munites = new Date().getTimezoneOffset();
       var hour = parseInt(munites / 60);
     var munite = munites % 60;
     var prefix = "-";
     if (hour < 0 || munite < 0) {
         prefix = "+";
         hour = -hour;
         if (munite < 0) {
              munite = -munite;
         }
     }
     hour = hour + "";
     munite = munite + "";
     if (hour.length == 1) {
         hour = "0" + hour;
     }
     if (munite.length == 1) {
         munite = "0" + munite;
     }
     var result = prefix + hour + munite;
     return result;
}

function replaceOffset(){
	var offset = getOffset();
	var indexa = offset.indexOf("+");
	var indexb = offset.indexOf("-");
	if(indexa!=-1){
		offset = "a" + offset.substring(1,offset.length);
	}else if(indexb!=-1){
		offset = "b" + offset.substring(1,offset.length);
	}
	return offset;
}