Business Days Between Dates Calculator

The calculator constructs JavaScript Date objects from the year, month, and day inputs and normalizes both to midnight (00:00:00) to eliminate any time-of-day ambiguity. It then checks that the end date is not earlier than the start date. The core algorithm iterates day-by-day from the start date to the end date using a while loop. On each iteration, it checks the day-of-week value (0 = Sunday, 6 = Saturday). Days with values 1–5 are always counted as business days. Days with values 0 or 6 increment the weekend counter and are added to the business day total only if the countWeekends toggle is enabled. The includeEndDate toggle controls whether the loop's boundary condition uses a strict less-than or a less-than-or-equal comparison, making it easy to switch between exclusive and inclusive counting conventions. Total calendar days and weekend days are tracked in parallel for transparency.