date-fns

About

Modern JavaScript date utility library

Live mirror of the GitHub README. Updated whenever the repo's default branch changes.

🔥️ NEW: date-fns v4.0 with first-class time zone support is out!

date-fns provides the most comprehensive, yet simple and consistent toolset for manipulating JavaScript dates in a browser & Node.js

👉 Documentation

👉 Blog

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It's like Lodash for dates

• It has 200+ functions for all occasions.
• Modular: Pick what you need. Works with webpack, Browserify, or Rollup and also supports tree-shaking.
• Native dates: Uses existing native type. It doesn't extend core objects for safety's sake.
• Immutable & Pure: Built using pure functions and always returns a new date instance.
• TypeScript: The library is 100% TypeScript with brand-new handcrafted types.
• I18n: Dozens of locales. Include only what you need.
• and many more benefits

import { compareAsc, format } from "date-fns";

format(new Date(2014, 1, 11), "yyyy-MM-dd");
//=> '2014-02-11'

const dates = [
  new Date(1995, 6, 2),
  new Date(1987, 1, 11),
  new Date(1989, 6, 10),
];
dates.sort(compareAsc);
//=> [
//   Wed Feb 11 1987 00:00:00,
//   Mon Jul 10 1989 00:00:00,
//   Sun Jul 02 1995 00:00:00
// ]

The library is available as an npm package. To install the package run:

npm install date-fns --save

Docs

See date-fns.org for more details, API, and other docs.

License

MIT © Sasha Koss

Quick facts

How Sourcemap Explorer detects date-fns

We catch date-fns from two complementary signals: bundled source paths and the embedded package.json. Modern bundlers (webpack, Vite, esbuild, Rollup, Turbopack) preserve the original node_modules/date-fns/ paths inside the JavaScript sourcemap's sources[] array — that's the canonical signal. When the matching package.json is also captured in sourcesContent[], we read the exact version field — patch number included. No regex guessing, no version inference.

1. 1

   Confirm the site exposes sourcemaps

   In DevTools Network, check the response headers of any application script for `SourceMap` or `X-SourceMap`. Failing that, fetch the script's last 4 KB and look for a `//# sourceMappingURL=` comment.

2. 2

   Find the package in the bundle

   Open DevTools → Network → reload. Click any application script and look at its sourcemap. Inside, search `sources[]` for entries matching `node_modules/date-fns/` — every match confirms the package is bundled. The matching `sourcesContent[i]` for `node_modules/date-fns/package.json` gives you the exact installed version.

3. 3

   Read the version directly from package.json

   Run `jq -r '. as $m | $m.sources | to_entries[] | select(.value | endswith("node_modules/date-fns/package.json")) | $m.sourcesContent[.key] | fromjson | .version' bundle.js.map`. Sourcemap Explorer automates the same query in the popup.

Recent versions

FAQ