var preYear = month-1<0 ? year-1 : year;
var preMonth = month-1<0 ? 11 : month-1;
preMonthDays = getSolarMonthDays(preYear,preMonth);
var preYear = month-1<0 ? year-1 : year;
var preMonth = month-1<0 ? 11 : month-1;
preMonthDays = getSolarMonthDays(preYear,preMonth);