dayjs

A minimalist JavaScript date library that mirrors the Moment.js API closely enough that the README claims existing Moment users already know how to use it. The whole library is described at 2kB.

Day.js is a minimalist JavaScript library that parses, validates, manipulates, and displays dates and times for modern browsers, with a largely Moment.js-compatible API. The README makes the migration case in one line: if you use Moment.js, you already know how to use Day.js. That compatibility is the main draw, and the GitHub description frames the library as an alternative to Moment.js with the same modern API while weighing in at 2kB. The homepage is day.js.org.

The feature list is short and familiar. A familiar Moment.js API and patterns, immutability, chainability, internationalization support, a 2kB library size, and support for all browsers. Immutability in particular matters for date work, since it means operations return new objects instead of mutating the one you already have. The README is translated into several languages, including Chinese, Japanese, Korean, Spanish, Russian, Turkish, and Hebrew, which is a small signal about the project's reach.

Plugins are described as independent modules that can be added to Day.js to extend functionality or add new features, which lets the core stay small while capabilities load on demand. Sponsorship is invited with a simple pitch: support the project by becoming a sponsor, and your logo shows up in the repository with a link to your website. The project is JavaScript with an MIT license, and its README is translated into a long list of languages, from Simplified Chinese and Japanese through Spanish and Russian.

• Source 1 · Project repository
• Source 2 · README