JavaScript Intl.NumberFormat Guide

The Intl.NumberFormat API provides locale-aware number formatting for currencies, percentages, and more. Here's how to use it.

Best Practices#

Locale Handling:
✓ Use user's locale when possible
✓ Provide locale fallbacks
✓ Test with multiple locales
✓ Consider right-to-left locales

Currency:
✓ Use ISO 4217 currency codes
✓ Match locale to currency region
✓ Consider currencyDisplay option
✓ Handle accounting format

Performance:
✓ Cache formatter instances
✓ Reuse formatters
✓ Avoid creating in loops
✓ Use formatToParts for custom display

Avoid:
✗ Manual number formatting
✗ String concatenation for currency
✗ Ignoring locale differences
✗ Creating formatters repeatedly

Intl.NumberFormat provides comprehensive locale-aware number formatting for currencies, percentages, units, and general numbers. Use it instead of manual string manipulation to ensure correct formatting across different locales. Cache formatter instances for performance and use formatToParts when you need fine-grained control over the output display.

JavaScript Intl.NumberFormat Guide

Basic Usage#

Currency Formatting#

Percentage Formatting#

Unit Formatting#

Decimal Options#

Notation Options#

Sign Display#

Format to Parts#

Range Formatting#

Rounding Options#

Practical Examples#

Caching Formatters#

Best Practices#

Conclusion#

Share this article

Related articles

JavaScript Intl API Guide

JavaScript Intl.Collator Guide

JavaScript Intl.DateTimeFormat Guide