Intl.DateTimeFormat provides locale-aware date and time formatting. Here's how to use it effectively.
Basic Usage
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Date Styles
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Time Styles
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Combined Styles
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Custom Components
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Component Options
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Time Zones
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Format Parts
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Range Formatting
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Calendar Systems
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Numbering Systems
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Practical Utilities
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Performance Caching
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Best Practices
Locale Selection:
✓ Use user's locale when possible
✓ Fall back gracefully
✓ Test with multiple locales
✓ Consider regional variants
Formatting:
✓ Use dateStyle/timeStyle for consistency
✓ Cache formatter instances
✓ Use formatToParts for custom layouts
✓ Handle time zones explicitly
Performance:
✓ Reuse formatter instances
✓ Create formatters outside loops
✓ Cache by locale + options
✓ Use formatRange for intervals
Avoid:
✗ Creating formatters repeatedly
✗ Ignoring time zones
✗ Hardcoding date formats
✗ Assuming locale behavior
Conclusion
Intl.DateTimeFormat provides powerful, locale-aware date formatting. Use dateStyle and timeStyle for consistent formatting, handle time zones explicitly with the timeZone option, and cache formatter instances for performance. The formatToParts method enables custom formatting while respecting locale conventions.