date-fns Date Utility Patterns

Quick Guide: date-fns is a tree-shakeable set of pure functions — each returns a new Date and nothing mutates. Parse with parseISO for ISO strings or parse for custom formats, then check isValid, because v4 returns Invalid Date where v3 threw. Format tokens are Unicode TR35 (yyyy, dd, EEEE) and differ from Moment's. Timezone support lives in a companion package whose name depends on the major version.

Detailed Resources:

• examples/core.md — formatting, parsing with validation, arithmetic, boundaries, preset ranges
• examples/timezone.md — TZDate, the in option, transpose, DST detection, UTC classes
• examples/i18n.md — locale maps, localized month and weekday names, week start days
• examples/relative.md — distances, durations, relative-vs-absolute display
• examples/comparison.md — comparisons, interval generation, overlap detection, validation
• reference.md — format token table, function index, v4 breaking changes, Moment migration table