# js-joda/js-joda

:clock2: Immutable date and time library for javascript

Repository: https://github.com/js-joda/js-joda
Canonical: https://ross.abutalabs.com/products/js-joda
Homepage: http://js-joda.github.io/js-joda/
Language: JavaScript
License: NOASSERTION
License Family: other
Topics: date, time, timezone, threeten, joda, immutable
Last push: 2026-08-24T10:32:12+00:00

## Health v2 (maintenance only)
Score: 67/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 8, longevity 100
- inputs: {"age_days": 3974, "days_push": 9, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1664, forks 131 (observed 2026-08-28T04:05:18.865794+00:00)

## What it is
js-joda is an immutable date and time library for JavaScript, ported from the Java threeten-backport (JSR-310 / java.time). It provides a domain-driven API with classes like LocalDate, LocalTime, LocalDateTime, and ZonedDateTime, with built-in ISO 8601 parsing and formatting.

## Use cases
- handle dates without times like birthdays or holidays safely
- parse and format ISO 8601 / RFC 3339 date strings
- work with timezone-aware date-times in JavaScript
- use immutable date objects in React or Flux apps
- replace moment.js with a faster standalone date library
- persist dates to a server without timezone ambiguity

## When to choose
- you need a standalone date-time implementation not wrapping native Date
- you want immutability and a domain-driven API like java.time
- performance matters - it is 2-10x faster than other date libraries
- you need robust ISO 8601 parsing and formatting

## When to avoid
- you only need trivial date formatting and prefer a tiny wrapper around native Date
- you need non-ISO calendar systems like Hijri or Buddhist calendars
- your project already uses Temporal API support in modern runtimes

## Facets
- artifact type: library
- maturity: stable
- function: date-time, parser, serialization
- domain: developer-tools, web-development
- platform: browser, cross-platform
- tags: immutable, iso-8601, timezone, threeten, joda, javascript, localization, nodejs

## Member repositories
- js-joda/js-joda (main) score 67

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:18.865794+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:44:29.357527+00:00, confidence not recorded.
  - readme: https://github.com/js-joda/js-joda (fetched 2026-08-28T04:05:18.865794+00:00, sha 6bd5d272826e)
  - homepage: http://js-joda.github.io/js-joda/ (fetched 2026-08-29T11:16:58.071495+00:00, sha 24d684ac161b)
  - registry_npm: https://registry.npmjs.org/js-joda (fetched 2026-08-29T11:16:58.075317+00:00, sha 35918d56ec8c)
- Data as of 2026-08-30T08:39:29.467469+00:00.