<!--{"section": "tjs", "type": "example", "group": "patterns", "order": 10, "parent": "tjs-patterns.md"}-->

# Date Formatting (with import)

Uses date-fns for date formatting via ESM import

```tjs:inline
TjsCompat
/#
## Date Formatting with Imports

This example demonstrates importing an external ESM module
(date-fns) and using it with TJS type safety.
#/

import { format, formatDistance, addDays, parseISO } from 'date-fns'

// Format a date with various patterns
function formatDate(date: '2024-01-15', pattern: 'yyyy-MM-dd'): '' {
  const parsed = parseISO(date)
  return format(parsed, pattern)
}

// Get human-readable relative time
function timeAgo(date: '2024-01-15'): '' {
  const parsed = parseISO(date)
  return formatDistance(parsed, new Date(), { addSuffix: true })
}

// Add days to a date
function addWorkdays(date: '2024-01-15', days: 5): '' {
  const parsed = parseISO(date)
  const result = addDays(parsed, days)
  return format(result, 'yyyy-MM-dd')
}

// Complex date operation with validation
function createEvent(input: {
  title: 'Meeting',
  startDate: '2024-01-15',
  durationDays: 1
}): { title: '', start: '', end: '', formatted: '' } {
  const start = parseISO(input.startDate)
  const end = addDays(start, input.durationDays)

  return {
    title: input.title,
    start: format(start, 'yyyy-MM-dd'),
    end: format(end, 'yyyy-MM-dd'),
    formatted: `${input.title}: ${format(start, 'MMM d')} - ${format(end, 'MMM d, yyyy')}`
  }
}

// Try them
console.log(formatDate('2024-01-15', 'MMMM d, yyyy'))
console.log(addWorkdays('2024-01-15', 5))
console.log(createEvent({ title: 'Launch', startDate: '2024-03-01', durationDays: 2 }).formatted)
```