How does daylight saving time (DST) affect date and time calculations?

Civil clocks shift by ±1 hour during Daylight Saving Time (DST) spring-forward and fall-back transitions. To prevent calendar days from erroneously computing as 23 or 25 solar hours, TimeDateStack standardizes target calendar calculations to UTC midnight (00:00:00.000Z), ensuring integer-accurate day shifts regardless of local civil time adjustments.

What is the Gregorian leap year formula used in date shift math?

A year is a leap year if it is evenly divisible by 4, except for century years (ending in 00), which must also be divisible by 400. In code: (year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0). When shifting across February in leap years like 2024 or 2028, 29 days are accurately allocated.

How do business days differ from calendar days in shift calculations?

Calendar day shifts add or subtract consecutive solar days including Saturdays and Sundays. Business day shifts advance only across Monday through Friday, skipping weekends and optionally observed statutory public holidays.

How do month additions handle varying month lengths (e.g., February or 30-day months)?

When adding calendar months to a date that falls on the 31st (such as January 31), if the target month has fewer days (like February with 28 or 29 days), standard date arithmetic automatically clamps the result to the last valid day of that target month to prevent unintentional month rollover.