Why should teams migrate away from Moment.js?

Moment.js is officially in maintenance mode. Its monolithic architecture cannot be tree-shaken, imposing ~70KB gzip overhead on web applications.

Does date-fns support timezones?

Yes, via the companion package `@date-fns/tz` or `date-fns-tz`, which relies on standard browser Intl APIs without heavy zone databases.

Moment.js → date-fns v3/v4Automated Breaking Change Check

Migrate Moment.js to date-fns (Zero Bundle Bloat)

Convert legacy mutable Moment.js operations into pure, tree-shakeable date-fns functions. Reduce JavaScript bundle weight by up to 70KB.

From: Moment.js

→

To: date-fns v3/v4

Source (Moment.js)

242 chars

Migrated Target (date-fns v3/v4)

1ms267 chars

import { format, addDays, differenceInDays, isBefore } from 'date-fns';

const now = moment();
const formatted = format(new Date(), 'YYYY-MM-DD');
const nextWeek = addDays(now, 7);
const isPast = isBefore(nextWeek, now);
const diff = differenceInDays(nextWeek, now);

Detected Breaking Changes & Semantic Shifts (2)

Immutable Date Instances

breaking

Unlike Moment.js which mutates date objects in-place, date-fns functions are pure and return new Date instances.

Resolution: Assign the return value: `const tomorrow = addDays(date, 1);`.

Import Format Helpers

info

date-fns uses individual named function imports to enable modern tree-shaking and zero bundle bloat.

Resolution: Import specific functions: `import { format, addDays, isBefore } from "date-fns";`.

How to Migrate from Moment.js to date-fns v3/v4

1
Paste your JavaScript or TypeScript code utilizing `moment()`.
2
The migrator replaces chained mutations with pure date-fns functional imports.
3
Date format tokens (YYYY-MM-DD -> yyyy-MM-dd) are updated to ISO standard tokens.
4
Export the tree-shakeable code and remove `moment` from your project dependencies.

Prevent Moment.js Re-introduction

package.json

"scripts": {
  "check-deps": "bunx depcheck --ignores=moment"
}

Run Migration via Terminal CLI

Perform identical migration routines across entire directories or repositories in your local terminal:

devflow migrate moment-to-date-fns -i src/utils/date.ts

npm / Node.jsBun Runtime

Migrate npm package.json to Bun Runtime & Scripts

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JestVitest

Migrate Jest Unit Tests to Vitest

Convert Jest test suites, configs, and mocks to Vitest. Share identical Vite configurations and execute tests 4x faster with ESM native workers.

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Bundle Size Analyzer

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Frequently Asked Questions

Why should teams migrate away from Moment.js?: Moment.js is officially in maintenance mode. Its monolithic architecture cannot be tree-shaken, imposing ~70KB gzip overhead on web applications.
Does date-fns support timezones?: Yes, via the companion package `@date-fns/tz` or `date-fns-tz`, which relies on standard browser Intl APIs without heavy zone databases.

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