When JavaScript Decided My Day Starts at 9AM
9 months ago
- #JavaScript
- #Date Handling
- #Time Zones
- new Date('2000-01-01') creates a date at midnight UTC, not local time.
- In Japan (UTC+9), this results in 2000-01-01T09:00:00, causing dashboard filters to miss data before 9AM.
- The bug occurred because the Date constructor assumed UTC, leading to incorrect comparisons.
- The fix involves explicitly setting the time to midnight local time and adjusting the max date range.
- Lessons include being cautious with date string interpretations and preferring explicit time settings.