dayjs

library1.11.20jsnpmunverified

Day.js is a minimalist JavaScript library providing a Moment.js-compatible API for parsing, validating, manipulating, and displaying dates and times. At only 2KB, it offers immutability, chainable methods, and extensive internationalization and plugin support. The current stable version is 1.11.20, and the library is actively maintained with frequent bug fix releases.

data

npm install dayjs

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INSTALL

IMPORT

SIG · DAYJS

dayjs

datajavascriptv1.11.20

Install

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Import

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Disk

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Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

dayjs

✓ import dayjs from 'dayjs'

✗ const dayjs = require('dayjs')

For ESM environments, use default import. CJS also supported.

Initializes a Day.js instance for the current date, then manipulates it by setting the year, adding a day, moving to the start of the month, and finally formats it into a specific string.

import dayjs from 'dayjs'; const formattedDate = dayjs().startOf('month').add(1, 'day').set('year', 2018).format('YYYY-MM-DD HH:mm:ss'); console.log(formattedDate); // Example output: '2018-01-02 00:00:00'

Debug

Known issues

gotchaMany common date manipulation and query functions (e.g., `isBetween`, `utc`, `duration`, `advancedFormat`) are not included in the core library. They must be explicitly imported and extended as plugins.

fix

Import the required plugin and extend Day.js: `import isBetween from 'dayjs/plugin/isBetween'; dayjs.extend(isBetween);`

affects: >=1.0.0

gotchaDay.js only includes the `en` locale by default. To use other locales, you must import them separately and then activate them globally or per instance.

fix

Import the locale: `import 'dayjs/locale/es';` then activate: `dayjs.locale('es');`

affects: >=1.0.0

gotchaDay.js instances are immutable. Methods like `add()`, `subtract()`, `set()`, `startOf()`, `endOf()` return a *new* Day.js instance rather than modifying the original. Assign the result to a new variable or chain methods.

fix

Store the result of manipulation: `const newDay = originalDay.add(1, 'day');`

affects: >=1.0.0

gotchaThe `diff()` method returns an integer difference by default. To get a floating-point number for the difference, you must pass `true` as the third argument.

fix

Use `dayjsA.diff(dayjsB, 'month', true)` for fractional differences.

affects: >=1.0.0

gotchaDay.js parsing is not as strict as some other libraries. For explicit and strict parsing of specific date formats, the `CustomParseFormat` plugin is often required.

fix

Import and use the `CustomParseFormat` plugin for precise parsing: `import customParseFormat from 'dayjs/plugin/customParseFormat'; dayjs.extend(customParseFormat); dayjs('12-25-1995', 'MM-DD-YYYY');`

affects: >=1.0.0

Errors

Common errors & fixes

ReferenceError: dayjs is not defined

Attempting to use `dayjs` without importing it first.

fix

Add `import dayjs from 'dayjs';` at the top of your file.

TypeError: dayjs(...).isBetween is not a function

Attempting to use a plugin-provided method (like `isBetween`, `utc`, `duration`) without importing and extending its respective plugin.

fix

Import the specific plugin and extend Day.js with it: `import isBetween from 'dayjs/plugin/isBetween'; dayjs.extend(isBetween);`

Invalid Date

Day.js could not parse the provided date string into a valid date object, especially for non-standard formats.

fix

Ensure the date string is in a standard format (ISO 8601, JavaScript Date string), or use the `CustomParseFormat` plugin for specific formats: `dayjs.extend(customParseFormat); dayjs('25/12/1995', 'DD/MM/YYYY');`

dayjs is not a function

Incorrectly importing Day.js (e.g., `import { dayjs } from 'dayjs'` instead of `import dayjs from 'dayjs'`).

fix

Ensure you are using the default import for the main Day.js function: `import dayjs from 'dayjs';`

Locale not applying to dates

The desired locale was imported but not activated globally or for the specific Day.js instance.

fix

After importing the locale file (e.g., `import 'dayjs/locale/fr';`), activate it using `dayjs.locale('fr');` for global effect or `.locale('fr')` on an instance for local effect.

Upgrade

Version history

1.11.20latest on npm

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Dependencies

No dependency data recorded yet.

Agent activity

15 hits · last 30 days

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Resources

githubhttps://github.com/iamkun/dayjs ↗

packagehttps://www.npmjs.com/package/dayjs ↗

homepagehttps://day.js.org ↗