bangla-support

Utility functions for Bangla (Bengali) digits and the Bangla calendar — dates, months, seasons and weekdays for Bangladesh (BD) and India (IN). Zero dependencies, ESM, fully typed.

Installation

npm install bangla-support

Requires Node.js >= 20.17. The package is ESM-only (import); modern Node can also require() it.

Quick start

import {getBanglaDate, getBanglaDigit, isBanglaDigit} from 'bangla-support'

getBanglaDate(new Date('2026-04-14T10:00:00+06:00'))
// 'মঙ্গলবার, ১ বৈশাখ, ১৪৩৩'

getBanglaDigit(1234567890) // '১২৩৪৫৬৭৮৯০'
isBanglaDigit('১২৩৪')      // true

The timezone contract

An input Date is an absolute instant. The output is the Bangla date at that instant in the selected country's timezone — Asia/Dhaka (UTC+6:00) for country: 'BD' (the default), Asia/Kolkata (UTC+5:30) for country: 'IN'.

This means the result does not depend on the machine or browser timezone. If it is 9 PM on April 13 in New York, it is already past midnight on April 14 in Dhaka — so getBanglaDate() correctly reports ১ বৈশাখ, the new year. Every function in this package follows the same rule.

API

All calendar functions share the signature fn(date?, options?):

• date — a Date (defaults to new Date()). Anything that is not a valid Date throws Error('Invalid Date').
• options.country — 'BD' (default) or 'IN'.
• options.format — a format token, where noted below.

getBanglaDate(date?, options?)

The composed, formatted Bangla date.

getBanglaDate(new Date('2026-04-14T10:00:00+06:00'))
// 'মঙ্গলবার, ১ বৈশাখ, ১৪৩৩'  (default format: 'eeee, D MMMM, YYYY')

getBanglaDate(new Date('2026-04-14T10:00:00+06:00'), {format: 'DD-MM-YY'})
// '০১-০১-৩৩'

Format tokens

| Token | Meaning | Example output | |-------|---------|----------------| | eeee | full weekday | মঙ্গলবার | | eee | short weekday | মঙ্গল | | D | day of month | ১ | | DD | day, zero-padded | ০১ | | M | month number | ১ | | MM | month number, zero-padded | ০১ | | MMMM | month name | বৈশাখ | | YY | 2-digit year | ৩৩ | | YYYY | full year | ১৪৩৩ | | YYYYb | year with era suffix | ১৪৩৩ (বঙ্গাব্দ) |

Format-string limitations: tokens are replaced by sequential, case-insensitive matching. A lowercase token (d, mm, yyyy) is recognized but renders the default variant of its group (D, MMMM, YYYY). There is no escape syntax — literal d/e/m/y letters in a format string will be treated as tokens, so stick to separators like spaces, commas, dashes and Bangla text.

getBanglaDay(date?, options?)

Day of the Bangla month. format: 'D' (default) or 'DD'.

getBanglaDay(new Date('2026-04-14T10:00:00+06:00'))                 // '১'
getBanglaDay(new Date('2026-04-14T10:00:00+06:00'), {format: 'DD'}) // '০১'

getBanglaMonth(date?, options?)

Bangla month. format: 'MMMM' (default), 'MM', or 'M'.

getBanglaMonth(new Date('2026-04-14T10:00:00+06:00'))                // 'বৈশাখ'
getBanglaMonth(new Date('2026-04-14T10:00:00+06:00'), {format: 'M'}) // '১'

getBanglaYear(date?, options?)

Bangla year (বঙ্গাব্দ). format: 'YYYY' (default), 'YY', or 'YYYYb'.

getBanglaYear(new Date('2026-04-14T10:00:00+06:00'))                    // '১৪৩৩'
getBanglaYear(new Date('2026-04-14T10:00:00+06:00'), {format: 'YYYYb'}) // '১৪৩৩ (বঙ্গাব্দ)'

getBanglaDayName(date?, options?)

Weekday name. format: 'eeee' (default, full) or 'eee' (short).

getBanglaDayName(new Date('2026-04-14T10:00:00+06:00'))                  // 'মঙ্গলবার'
getBanglaDayName(new Date('2026-04-14T10:00:00+06:00'), {format: 'eee'}) // 'মঙ্গল'

getBanglaSeason(date?, options?)

The season (ঋতু) — one of the six Bangla seasons, two months each. A format option, if passed, is ignored.

getBanglaSeason(new Date('2026-07-06T12:00:00+06:00')) // 'বর্ষা'

getBanglaDigit(digit?)

Convert Latin digits to Bangla numerals. Non-digit characters pass through unchanged. With no argument, returns the (frozen) array of the ten Bangla digit characters.

getBanglaDigit(2026)    // '২০২৬'
getBanglaDigit(3.14)    // '৩.১৪'
getBanglaDigit(0)       // '০'
getBanglaDigit('ID-42') // 'ID-৪২'
getBanglaDigit()        // ['০','১','২','৩','৪','৫','৬','৭','৮','৯']

isBanglaDigit(value)

true when the value consists only of Bangla digit characters.

isBanglaDigit('১২৩') // true
isBanglaDigit('123') // false
isBanglaDigit('১2৩') // false

getBanglaDays(format?), getBanglaMonths(), getBanglaSeasons()

The constant lists. Returned arrays are frozen — copy before mutating.

getBanglaDays()        // ['রবি', 'সোম', 'মঙ্গল', ...]
getBanglaDays('eeee')  // ['রবিবার', 'সোমবার', 'মঙ্গলবার', ...]
getBanglaMonths()      // ['বৈশাখ', 'জ্যৈষ্ঠ', ...]
getBanglaSeasons()     // ['গ্রীষ্ম', 'বর্ষা', ...]

BD vs IN calendars

• country: 'BD' follows the revised Bangladesh calendar (Bangla Academy, 2019): fixed month lengths, new year on April 14, Falgun gaining a day in Gregorian leap years. The test suite verifies it against published dates (পহেলা বৈশাখ, একুশে ফেব্রুয়ারি = ৮ ফাল্গুন, and every month start).
• country: 'IN' approximates the astronomical (Surya Siddhanta-style) Bengali calendar used in West Bengal. Because published panjikas differ by tradition (and sometimes by a day), this mode's output is pinned by tests but not certified against a single authority.

Contributing

See CONTRIBUTING.md. Bug reports with a failing date example are especially welcome.

License

MIT © Abdur Rahman Robin