momentjs.com

One-line Overview

momentjs.com is the official website for Moment.js, the classic JavaScript date-handling library, maintained by a US-based developer team. Once the most popular tool for date parsing, formatting, and manipulation in frontend development, Moment.js was almost synonymous with “date library.” Although the project has officially entered maintenance mode and the team recommends using Luxon for new projects, a huge number of legacy projects and older codebases still depend on it, so it remains hard to ignore.

Business Details

Moment.js itself is an open-source JavaScript library, while momentjs.com provides the official documentation, API reference, and version downloads. First released in 2011, the project quickly became popular thanks to its intuitive chainable API and extensive internationalization support, at one point becoming one of the most downloaded packages on npm, with monthly downloads in the tens of millions. Its users range from individual developers to large enterprises, and well-known projects such as GitHub and WordPress have used, or still use, it.

However, as frontend engineering has placed greater emphasis on bundle size and performance, Moment.js’s “all-in-one” design has drawn criticism—by default it includes all locale files, and the uncompressed version is over 300KB. In 2020, the official team announced that the project had entered maintenance mode: no new features would be added, only critical bugs and security issues would be fixed, and new projects were strongly encouraged to use the lighter, immutable Luxon instead. Today, momentjs.com mainly serves as an archive for historical documentation and migration guidance.

Who Is It For?

Moment.js is best suited for developers maintaining older projects. If the codebase you have inherited or maintain already relies heavily on Moment.js, and a full replacement would be too costly in the short term, continuing to use it is a pragmatic choice. For rapid prototyping or small utility projects that are not sensitive to bundle size, Moment.js’s ease of use can also save time.

For individual developers learning date-handling APIs, Moment.js has clear documentation and plenty of examples, making it beginner-friendly. However, it is not recommended for new projects or scenarios with strict requirements around performance and bundle size, especially modern framework projects such as React or Vue. The official team also explicitly recommends using Luxon or Day.js instead. Enterprise applications that require long-term maintenance should prioritize a proactive migration plan.

Key Features and Highlights

• Date parsing and formatting: Supports parsing of almost any string format, such as “2023-01-15T10:30:00Z”, and provides a flexible format() method for custom output formats, such as “YYYY年MM月DD日”.
• Chainable operations and calculations: Methods such as .add(), .subtract(), .startOf(), and .endOf() make date arithmetic and range calculations readable and straightforward.
• Time zone support: With the moment-timezone plugin, it can handle cross-time-zone conversions, making it suitable for international applications.
• Internationalization (i18n): Includes 100+ locale packs for displaying months, weekdays, and more in multiple languages, though loading all locales by default can hurt performance.
• Relative time: Methods such as fromNow() and calendar() can quickly generate human-readable strings like “3 days ago” or “tomorrow at 2 PM”.
• Type-safety limitations: Moment objects are mutable and comparable, but the official team has acknowledged that immutable design is better—one of the key directions improved by Luxon.

Pricing Analysis

Moment.js is open source and free, and momentjs.com does not charge any fees. All features, documentation, and version updates are available to developers without paid subscriptions or licenses. In terms of pricing, it sits firmly in the “zero-cost” category.

That said, its “maintenance mode” status means there will be no future performance optimizations or new features, so long-term use may create hidden maintenance costs through technical debt. For new projects, although Moment.js is free, choosing a more modern library such as Day.js, which is only 2KB, can reduce bandwidth usage and load time, indirectly lowering operating costs. In other words, the value of Moment.js depends on the project stage: it is free and practical for legacy projects, but you must accept technical stagnation; for new projects, it is also free, but the long-term cost may be higher.

How Chinese Users Can Use It

momentjs.com is directly accessible from mainland China without needing a VPN or proxy, and documentation loading speed is generally acceptable. When installing the moment package via npm, domestic mirrors such as Taobao npm usually sync properly, so there are no major network barriers.

Since Moment.js is completely free, there is no purchase process and no need to consider payment methods. Invoicing is also not applicable—open-source projects do not provide commercial invoices. For developers in China who must use Moment.js due to project requirements, it can be introduced directly via npm or a CDN.

If considering alternatives, Day.js and date-fns are both lighter options with relatively compatible APIs and good Chinese community support. New projects should evaluate these libraries first to avoid getting stuck in the maintenance burden of Moment.js.

Pros and Cons

Pros:

• ✅ Extremely detailed documentation with rich examples and a gentle learning curve
• ✅ Comprehensive functionality covering most date-operation scenarios
• ✅ Huge community, with a vast number of answers on Stack Overflow
• ✅ Excellent compatibility, including support for older browsers such as IE9+
• ✅ Zero cost, open source and free

Cons:

• ❌ Large bundle size, around 60KB minified and about 20KB after gzip, affecting initial page load
• ❌ Mutable objects can easily introduce hard-to-track side effects
• ❌ Already in maintenance mode, with no new feature updates
• ❌ Loads all locale files by default, causing redundancy
• ❌ Performance is weaker than modern libraries, with Day.js being roughly 3-5 times faster

Comparison with Similar Products

• Day.js: A lightweight alternative to Moment.js at 2KB, with an API that is almost fully compatible. It supports plugin-based on-demand loading, offers better performance, and is still actively maintained. A top choice for new projects.
• Luxon: The officially recommended alternative, developed by the Moment.js team. It uses immutable objects and has built-in time zone support, but its API differs somewhat, so migration cost is moderate.
• date-fns: Uses a functional design, supports on-demand imports, avoids global pollution, and keeps bundle size under control. However, its usage is less intuitive than Moment.js’s chainable API, making it better suited to teams that prefer functional programming.

Final Recommendation

Moment.js is suitable for developers maintaining legacy codebases and for prototype projects that need quick validation of date logic. If you are starting a new project, regardless of size, it is strongly recommended to use Day.js or Luxon directly to avoid being forced into a technical-debt migration later.

For Chinese users, although Moment.js has no major network access issues, Day.js is generally more friendly in terms of Chinese documentation and community activity, especially within the ecosystem of popular frameworks such as Vue and React. If your project is already deeply tied to Moment.js, it is best to create a phased migration plan and prioritize replacing core modules first. In short, Moment.js is a historically important and highly respected library, but it is no longer suitable as the default choice for new projects.