targetMonth = 12; // 1 = Jan, 12 = Dec
targetDay   = 31;
targetYear  = new Date().getFullYear();
today = new Date();
// Convert to JS month index (0–11)
jsMonth = targetMonth - 1;
targetDate = new Date(targetYear, jsMonth, targetDay);
// If date passed, count for next year
if (today > targetDate) {
targetDate = new Date(targetYear + 1, jsMonth, targetDay);
}
// Calculate difference in days
oneDay = 1000 * 60 * 60 * 24;
diff = targetDate.getTime() - today.getTime();
daysLeft = Math.ceil(diff / oneDay);
daysLeft + " Days Left";