Skip to content
CAI
Produce a survey ↗Verify a survey

iamkun/dayjs

This system is a modular date and time manipulation library that provides a lightweight, chainable API for parsing, validating, manipulating, and formatting dates. It supports extensive internationalization with numerous locale files and offers a plugin architecture to extend functionality, including timezone handling, duration calculations, and compatibility with Moment.js. The codebase also includes comprehensive TypeScript definitions and test coverage to ensure reliability across various date operations and edge cases.

51.0

Adequate · 2 August 2026

17k

lines of production code

JavaScript

primary language

2

bus factor · 359 authors in all

3

measurements over time

CAI band scale
CAI trend line

How it got here

2018 · Plugin architecture and internationalization expansion

This period focused on modernizing the project's build system and expanding its plugin architecture to support features like relative time, week numbers, and date range comparisons. Simultaneously, the codebase underwent significant refactoring to improve modularity, with core logic and utilities restructured for better testability and performance.

16 changes

2019 · plugin architecture and type safety

This period focused on expanding the library's capabilities by introducing a modular plugin architecture, adding support for UTC, localization, and various date calculations. Concurrently, significant effort was dedicated to improving TypeScript type definitions to ensure robust type safety and autocomplete for both the core library and its new plugins.

17 changes

2020–2025 · Plugin ecosystem expansion

This period focused on significantly expanding the Day.js plugin ecosystem by introducing new capabilities for timezones, durations, and object-based date manipulation. The team also enhanced core parsing and comparison features, such as ISO week support and pluralized getters/setters, while adding development-time warnings to prevent common usage errors.

13 changes

CAI lens gauges

Survey your own repository

iamkun/dayjs was measured the same way every project in this corpus was: the same rubric, at a pinned commit, with the result published in full. Point the surveyor at a repository you know and see whether you agree with it.

Survey a repository

About this page

  • The description of this project is derived from its own commit history, not from its README.
  • The score is its highest published measurement, taken on 2 August 2026 at a pinned commit. It is not a live figure and does not change until the project is measured again.
  • Measured at commit 98364bcebc — the exact code this score is about.
  • Scored under rubric rubric-2026.08.18. Score the same commit under that rubric and you get the same number.
CAI link cards