Comparing
2KB immutable date time library alternative to Moment.js with the same modern API
TypeScript is a language for application scale JavaScript development
| Metric | dayjs | typescript |
|---|---|---|
| Ecosystem | npm | npm |
| Difficulty | Intermediate | Beginner ✓ |
| Weekly downloads | 43.9M | 176.4M↑ |
| Latest version | v1.11.20 | v6.0.2 |
| Recipes | 1 | 1 |
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Use Day.js when you need date parsing, formatting, arithmetic (add/subtract days/months), or comparisons in browser code where bundle size matters. Its plugin system covers timezones, relative time ('3 hours ago'), duration, and ISO weeks.
Use TypeScript for any JavaScript project that will grow beyond a few hundred lines or be worked on by more than one person. The upfront cost of adding types pays back quickly in editor autocomplete, safe refactoring, and catching bugs before runtime.
For complex timezone-aware calendar applications, consider Temporal (the upcoming TC39 proposal) or date-fns with explicit timezone handling. Day.js's plugin system can grow large if you need many features.
TypeScript adds a compilation step and a learning curve. For tiny scripts, config files, or throwaway code, plain JavaScript is faster to write. TypeScript's type system also has limits — it can't track runtime behaviour, only the shape of values at compile time.
dayjs
typescript