You-Dont-Need-Momentjs

# [You don't (may not) need Moment.js](https://you-dont-need.github.io/You-Dont-Need-Momentjs/#/)

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[Moment.js](https://momentjs.com/) is a fantastic time & date library with lots of great features and utilities. However, if you are working on a performance sensitive web application, it might cause a huge performance overhead because of its complex APIs and large bundle size.

![Large bundle size](./screenshot.png)

Problems with Moment.js:

- It is highly based on OOP APIs, which makes it fail to work with tree-shaking, thus leading to a huge bundle size and performance issues.
- It is mutable and it causes bugs:
  - [clone](https://momentjs.com/docs/#/parsing/moment-clone/)
  - [How do I work around mutability in moment.js?](https://stackoverflow.com/questions/30979178/how-do-i-work-around-mutability-in-moment-js)
- Complex OOP API (which doubles mutability problem). Here is an example:
  https://github.com/moment/moment/blob/develop/src/test/moment/add_subtract.js#L244-L286
  Moment.js allows to use `a.subtract('ms', 50)`, `a.subtract(50, 'ms')` and even `a.subtract('s', '50')`.

If you are not using timezone but only a few simple functions from moment.js, this might bloat your app, and therefore is considered overkill. [dayjs](https://github.com/iamkun/dayjs) has a smaller core and has very similar APIs so it makes it very easy to migrate. [date-fns](https://github.com/date-fns/date-fns) enables [tree-shaking and other benefits](https://github.com/date-fns/date-fns/issues/275#issuecomment-264934189) so that it works great with React, Sinon.js, and webpack, etc. See https://github.com/moment/moment/issues/2373 for more ideas on why and how people switch from moment.js to other solutions.

## Brief Comparison

| Name      | Tree-shaking | Methods richness | Pattern    | Locale | Timezone Support       | Popularity (stars)                                               | Sizes                                                                                                                        |
| --------- | ------------ | ---------------- | ---------- | ------ | ---------------------- | ---------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------- |
| Moment.js | No           | High             | OO         | 123    | Good (moment-timezone) | ![stars](https://flat.badgen.net/github/stars/moment/moment)     | ![raw](https://flat.badgen.net/bundlephobia/min/moment?label=min) ![size](https://flat.badgen.net/bundlephobia/minzip/moment?label=zip&color=purple)     |
| Luxon     | No           | High             | OO         | -      | Good (Intl)            | ![stars](https://flat.badgen.net/github/stars/moment/luxon)      | ![raw](https://flat.badgen.net/bundlephobia/min/luxon?label=min) ![size](https://flat.badg