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Locale Formatting ​

Problem ​

A timestamp needs locale-aware output without leaking the host timezone into server-rendered content.

Solution ​

Parse it as an instant and pass timeZone explicitly to format().

ts
import { format, formatRelative, parse } from '@vielzeug/tempo';

const event = parse('2026-03-21T10:15:30Z', { as: 'instant' });

const display = format(event, {
  locale: 'de-DE',
  pattern: 'long',
  timeZone: 'Europe/Berlin',
});

const relative = formatRelative(event, {
  base: parse('2026-03-21T08:15:30Z', { as: 'instant' }),
  locale: 'de-DE',
});

Pitfalls ​

  • pattern and intl are mutually exclusive.
  • Use formatInstant() for transport and log output.