Moment.js vs Day.js — Which One Should You Use Today?

Hi everyone! 👋

Welcome to my very first online article! 😄

This is actually my first time writing a technical post, so please bear with me if it’s not perfect. I'm open to feedback and discussion — feel free to drop your thoughts in the comments to keep me motivated and excited to share more!

---

🔍 Background

This article is inspired by a recent task I received from my team at work. We're currently working on a JavaScript-based project using Nuxt.js, and I was asked to research date manipulation libraries.

We had previously used Moment.js, but I kept encountering discussions comparing it to Day.js — some even questioned whether Moment.js was still relevant. That piqued my curiosity.

So I ran a quick technical comparison between the two. Rather than saying one is "better", I wanted to understand where each library excels and what trade-offs they offer. Hopefully, this post helps you make the right choice for your use case too!

---

🆚 Moment.js vs Day.js

Here’s a side-by-side comparison of the two popular JavaScript libraries for date and time handling.

---

📆 Moment.js

• Released: September 15, 2011
• Created by: Tim Wood
• Purpose: Simplify date parsing, validation, manipulation, and formatting with a developer-friendly API.

🔍 Project Status

• As of 2020, Moment.js is in maintenance mode.
• No new features are planned, but bug fixes and security updates may still be provided.
• Reference – Project Status

---

📆 Day.js

• Released: May 23, 2018
• Created by: @iamkun
• A modern and lightweight alternative to Moment.js, with a similar API.

✨ Strengths of Day.js

• Small bundle size (~2KB without plugins)
• Fast performance
• Immutable date objects
• Tree-shaking friendly
• Plugin-based system for optional features
• Compatible with modern frameworks like Vue, Nuxt, and React

---

📊 Quick Comparison Table

📦 Moment.js on Bundlephobia

📦 Day.js on Bundlephobia

---

🎯 When to Use What?

Here’s a quick guide to help you decide:

✅ Use Moment.js if:

• You're maintaining or working on a legacy codebase.
• You need comprehensive parsing and timezone support out-of-the-box.
• Bundle size is not a major concern.

✅ Use Day.js if:

• You're building a modern application where performance and size matter.
• You prefer immutability and a modular plugin system.
• You're using frameworks like Vue, Nuxt, React, etc.

---

🧠 Conclusion

Both Moment.js and Day.js are powerful in their own ways.

• Moment.js remains a mature and battle-tested option for robust date handling, especially in older codebases.
• Day.js offers a more modern take, focused on size, speed, and simplicity — while keeping the familiar API.

Rather than suggesting one is strictly "better" than the other, I hope this article shows how they serve different needs depending on your project context.

---

💡 Final Thoughts

If you're starting a new JavaScript project, it’s worth evaluating Day.js for its modern architecture and smaller footprint.

If you're maintaining a legacy project, Moment.js might still be the more practical choice, but keep in mind its status.

Ultimately, the best tool is the one that fits your project’s requirements, team familiarity, and long-term maintainability goals.

---

🙏 Thank You

Thanks so much for reading my first blog post!

I hope this helped clarify the differences and use cases between Moment.js and Day.js. If you’ve used either (or both), I’d love to hear your experience in the comments!

💻 Check out the small experiment I built:

👉 Live Demo – GitHub Pages

Until next time — happy coding and keep learning! 🚀