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Guide · Open source

How to use You-Dont-Need-Momentjs: replace Moment.js tasks

Updated · written with AI from the project's own documentation and checked against our catalogue data

You-Dont-Need-Momentjs is a reference guide, not a runnable program. It lists common date and time tasks such as parsing, formatting, adding, subtracting and comparing, and shows how to do each one without Moment.js, using native JavaScript or smaller libraries like date-fns and dayjs. It is aimed at developers who want a smaller bundle or a side-by-side reference for migrating away from Moment.js.

You Don't Need Moment.jsyou-dont-need/You-Dont-Need-Momentjs · ★ 13.3k · MIT

Quick start

  1. 1Read the task you need. Open the Quick Links section and find the date or time task your code performs, such as parsing or adding time.
  2. 2Check the feature parity table. Look up that task to see whether native JavaScript, date-fns, dayjs or another option covers it, and where extra work is needed.
  3. 3Compare the libraries. Use the comparison table to weigh tree-shaking, method richness, pattern and timezone support for your project.
  4. 4Install the ESLint plugin. Run npm install --save-dev eslint-plugin-you-dont-need-momentjs in a project that already uses ESLint and Node.js with npm.
  5. 5Update your ESLint config. Add plugin:you-dont-need-momentjs/recommended to the extends setting in your ESLint configuration.
  6. 6Replace the flagged code. Rewrite the flagged Moment.js calls using the approach shown in the matching guide section.

Who should read this guide?

The guide is written for developers maintaining a web app that loads Moment.js and wants a smaller bundle, and for teams planning a migration who want a reference to compare APIs. It also suits projects that only use a few simple Moment.js functions.

The README says that if you are not using timezones but only a few simple functions from Moment.js, the library may be overkill for your app.

  • Good fit: a web app where bundle size matters and only basic date tasks are needed.
  • Good fit: a team comparing Moment.js with native JavaScript, date-fns and dayjs before migrating.
  • Poor fit: an app that relies heavily on Moment.js timezone features. The README says Moment.js timezone support is good through moment-timezone.

Why the guide says to move away from Moment.js

The README gives two main reasons. First, Moment.js is based on OOP APIs, which the README says makes it fail to work with tree-shaking, leading to a large bundle size and performance issues. Second, Moment.js is mutable, which the README says causes bugs. It points to moment's clone method and a Stack Overflow question about working around mutability.

The README also notes that Moment.js allows several forms of the same call, such as a.subtract('ms', 50), a.subtract(50, 'ms') and a.subtract('s', '50').

Compare the alternatives

The README includes a comparison table of Moment.js, Luxon, date-fns and dayjs. It lists tree-shaking support, method richness, pattern (OO or functional), locale count and timezone support. According to the table, date-fns supports tree-shaking and uses a functional pattern, while Moment.js, Luxon and dayjs do not list tree-shaking support.

The README describes dayjs as having a smaller core and very similar APIs, which it says makes migration easy. It describes date-fns as enabling tree-shaking, so it works well with React, Sinon.js and webpack.

  • Native: built-in JavaScript Date and Intl APIs, with no extra dependency.
  • date-fns: functional, tree-shakeable, timezone support via date-fns-tz.
  • dayjs: OO pattern with a smaller core and an API close to Moment.js.
  • Luxon and Temporal polyfill are listed as comparable projects in the guide's feature parity table.

Find a task in the guide and check the feature parity table

The guide's Quick Links section groups tasks under Parse, Get + Set, Manipulate, Display and Query. Each link goes to a section that shows how to do that task without Moment.js.

The Feature Parity table marks each task for Native, Luxon, date-fns, dayjs and Temporal. A warning symbol means other packages or extra work are needed for that task.

  • Parse: string with date format, string with time format, string with format and locale.
  • Get + Set: milliseconds to minutes, date of month, day of week, day of year, week of year, days in month, weeks in year.
  • Manipulate: add, subtract, start of time, end of time.
  • Display: format, time from now, time from X, difference.
  • Query: is before, is same, is after, is between, is leap year, is a date.

Install the ESLint plugin to find Moment.js usages

If you use ESLint, the README says you can install a plugin that helps identify places in your codebase where you do not (or may not) need Moment.js. You need Node.js and npm to install it, and ESLint itself. Install the plugin as a dev dependency with the command below.

After installing, the README says to update your config by adding the recommended preset to extends. The snippet in the README is shown below.

npm install --save-dev eslint-plugin-you-dont-need-momentjs

Add the plugin's recommended config

Once the package is installed, add the recommended config to the extends setting of your ESLint configuration, as shown in the README.

"extends" : ["plugin:you-dont-need-momentjs/recommended"],

What people use it for

  • Reducing bundle size in a web app that only formats or parses a few dates.
  • Planning a migration from Moment.js by comparing each function with its date-fns or dayjs equivalent.
  • Finding Moment.js calls across a codebase with the ESLint plugin.
  • Checking which tasks native JavaScript covers before adding a library.

Frequently asked questions

Is You-Dont-Need-Momentjs a library I can install?

No. The README describes it as a reference guide that lists how to do date and time tasks without Moment.js. The only package it names for installation is the ESLint plugin, eslint-plugin-you-dont-need-momentjs.

What do I need to install the ESLint plugin?

The README lists Node.js and npm for the ESLint plugin, along with ESLint itself. You install the plugin as a dev dependency with npm install --save-dev eslint-plugin-you-dont-need-momentjs.

Is it free to use and what is the licence?

The project is listed under the MIT licence. The README does not mention pricing for the guide or the plugin.

What should I use instead of Moment.js?

The guide covers several options rather than recommending one. It names native JavaScript, date-fns and dayjs, and lists Luxon and Temporal in its feature parity table. The right choice depends on your tasks and whether you need timezone features.

Does this guide work if my app uses timezones?

The README says Moment.js timezone support is good through moment-timezone, and the guide is aimed at apps that do not use timezones. If your app depends heavily on timezone features, the README suggests Moment.js may still be the better fit.

How does date-fns compare with dayjs for migration?

According to the README, dayjs has a smaller core and very similar APIs, which makes migration easy. date-fns enables tree-shaking and uses a functional pattern, which the README says works well with React and webpack.

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Our verdict

This guide suits developers who want to shrink a Moment.js-heavy app or plan a migration with a clear side-by-side reference, and the ESLint plugin helps find Moment.js calls. It is not a drop-in replacement, and projects that depend heavily on Moment.js timezone features should look elsewhere.

Install options & downloads