Why use Day.js?
- 🕒 Familiar Moment.js API & patterns
- 💪 Immutable
- 🔥 Chainable
- 📦 2kb mini library
- 👫 All browsers support
It's worth noting that the author doesn't claim 100% API compatibility with Moment.js, but they say it's close enough that "If you use Moment.js, you already know how to use Day.js."
If your app targets modern browsers and is currently packing Moment.js' 16.4kb in its JS bundle, maybe you can get by with Day.js' 2kb instead...