把当前时间转换成指定时区的时间时，运行结果不对，求高手解答！


        function convertTimezoon(dFromTime, nToTimezoon) {
            var sFromTime=dFromTime.toString();
            var nFromTimezoonH, nFromTimezoonM;
            var nTimeDifference, nToTime;            //把IE的时区转换为标准GMT时区
            if (sFromTime.indexOf("UTC") != -1) {
                if (sFromTime.indexOf("UTC+") != -1 || sFromTime.indexOf("UTC-") != -1) {
                    nFromTimezoonH = parseInt(sFromTime.substr(sFromTime.indexOf("UTC") + 3, 3), 10);
                    nFromTimezoonM = parseInt(sFromTime.substr(sFromTime.indexOf("UTC") + 6, 2), 10);
                }
                else {
                    nFromTimezoonH = 0;
                    nFromTimezoonM = 0;                   
                }
            }            if (sFromTime.indexOf("PST") != -1) {
                nFromTimezoonH = -8;
                nFromTimezoonM = 0;
            }            if (sFromTime.indexOf("MST") != -1) {
                nFromTimezoonH = -7;
                nFromTimezoonM = 0;
            }            if (sFromTime.indexOf("CST") != -1) {
                nFromTimezoonH = -6;
                nFromTimezoonM = 0;
            }            if (sFromTime.indexOf("EST") != -1) {
                nFromTimezoonH = -5;
                nFromTimezoonM = 0;
            }            //把非IE的时区转换为标准GMT时区
            if (sFromTime.indexOf("GMT") != -1) {
                nFromTimezoonH = parseInt(sFromTime.substr(sFromTime.indexOf("GMT") + 3, 3), 10);
                nFromTimezoonM = parseInt(sFromTime.substr(sFromTime.indexOf("GMT") + 6, 2), 10);
            }            //计算与所给时区(nToTimezoon)的时差
            if (nFromTimezoonH != null) {
                if (nFromTimezoonM != 0)
                    nTimeDifference = nToTimezoon - (nFromTimezoonH / Math.abs(nFromTimezoonH) * (Math.abs(nFromTimezoonH) + nFromTimezoonM/60));
                else
                    nTimeDifference = nToTimezoon - nFromTimezoonH;
            }            //把当前时间转换成所给时区(nToTimezoon)的时间
            var dTempTime = new Date();
            nToTime = new Date(dTempTime.getTime() + nTimeDifference * 60 * 60 * 1000);
            return nToTime;
        }