INTECH / OPEN SOURCE

Chronera.

Calendar dates and time zones.
Try it, then take the code.

JAVASCRIPT + TYPESCRIPTv0.2.8

npm install @intech-software/chronera@0.2.8

npm GitHub Get started

TRY CHRONERA / 3 EXAMPLES

Choose what to try

Change a value → Run → Copy the code

JavaScript is needed to change values. All three starting examples and their code are available below.

Display a Buddhist year

Enter a Gregorian date to see the same day in Thai and English.

RESULT

Thai · Buddhist calendar: 19 ตุลาคม 2569
English · Gregorian calendar: 19 October 2026

Results for the starting values.

JAVASCRIPT / ESM

Code and results come from the same run.

import { parseLocalDate, formatWithPattern } from '@intech-software/chronera';

const date = parseLocalDate("2026-10-19");
console.log(formatWithPattern(date, 'd MMMM yyyy', {
  locale: 'th-TH', calendar: 'buddhist', numberingSystem: 'latn',
}));
console.log(formatWithPattern(date, 'd MMMM yyyy', {
  locale: 'en-GB', calendar: 'gregory', numberingSystem: 'latn',
}));

What this code does: parseLocalDate reads a date without a time. The calendar option chooses how to display it; there is no need to add 543 yourself.

Compare time zones

Compare one event in the selected time zone and UTC.

RESULT

Selected time zone · Buddhist calendar: 19/10/2569 00:30
UTC · Gregorian calendar: 18/10/2026 17:30

Results for the starting values.

JAVASCRIPT / ESM

Code and results come from the same run.

import { parseInstant, formatWithPattern } from '@intech-software/chronera';

const instant = parseInstant("2026-10-18T17:30:00Z");
console.log(formatWithPattern(instant, 'dd/MM/yyyy HH:mm', {
  locale: 'th-TH', calendar: 'buddhist', numberingSystem: 'latn',
  timeZone: "Asia/Bangkok",
}));
console.log(formatWithPattern(instant, 'dd/MM/yyyy HH:mm', {
  locale: 'en-GB', calendar: 'gregory', numberingSystem: 'latn',
  timeZone: 'UTC',
}));

What this code does: parseInstant reads a timestamp with a UTC offset. timeZone chooses where to display that instant; it does not change the original event.

Add days across a year

Try December 31 plus one day, or use a negative number to go back.

RESULT

New date · Buddhist calendar: 01/01/2570
New date · Gregorian ISO: 2027-01-01

Results for the starting values.

JAVASCRIPT / ESM

Code and results come from the same run.

import { parseLocalDate, addDays, formatWithPattern } from '@intech-software/chronera';

const date = parseLocalDate("2026-12-31");
const result = addDays(date, 1);
console.log(formatWithPattern(result, 'dd/MM/yyyy', {
  locale: 'th-TH', calendar: 'buddhist', numberingSystem: 'latn',
}));
console.log(formatWithPattern(result, 'yyyy-MM-dd', {
  locale: 'en-GB', calendar: 'gregory', numberingSystem: 'latn',
}));

What this code does: addDays adds calendar days across months, years and leap days without changing the stored Gregorian year to a Buddhist year.

Chronera 0.2.8 · Runs on your device. Month names can vary with the runtime’s locale data.

Before using it

Full documentation

Install: Use Node.js 22.14 or newer, or an ESM bundler for a website.
Choose the data type: Use parseLocalDate for a date alone, and parseInstant for a timestamp with a UTC offset.
Format: Choose the language, calendar and time zone that match the task.

INTECH uses Chronera for article dates, project dates and project briefs.

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