MomentJS with Buddhist year

buddhist-year.js

module.exports = {
  toBuddhistYear: (moment, format) => {
    var christianYear = moment.format('YYYY')
    var buddhishYear = (parseInt(christianYear) + 543).toString()
    return moment
      .format(format.replace('YYYY', buddhishYear).replace('YY', buddhishYear.substring(2, 4)))
      .replace(christianYear, buddhishYear)
  }
}

index.js

const moment = require('moment-timezone')
const { toBuddhistYear } = require('./buddhist-year')
moment.locale('th')
console.log(toBuddhistYear(moment().tz('Asia/Bangkok'), 'LLLL'))

package.json

{
    "name": "moment-experiment",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "scripts": {
        "test": "mocha"
    },
    "author": "",
    "license": "ISC",
    "dependencies": {
        "moment": "^2.29.1",
        "moment-timezone": "^0.5.33"
    },
    "devDependencies": {
        "mocha": "^6.2.3"
    }
}

test.js

const assert = require('assert')
const moment = require('moment-timezone')
const { toBuddhistYear } = require('../buddhist-year')

describe('ToBuddhistYear', () => {
  it('Should return corrent date and time in LLLL format', () => {
    assert.strictEqual('Thursday, June 27, 2562 2:15 AM', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'LLLL'))
  })
  it('Should return correct date without time in LLLL format', () => {
    assert.strictEqual('Thursday, June 27, 2562 12:00 AM', toBuddhistYear(moment('2019-06-27'), 'LLLL'))
  })
  it('Should return corrent date and time in llll format', () => {
    assert.strictEqual('Thu, Jun 27, 2562 2:15 AM', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'llll'))
  })
  it('Should return correct date without time in llll format', () => {
    assert.strictEqual('Thu, Jun 27, 2562 12:00 AM', toBuddhistYear(moment('2019-06-27'), 'llll'))
  })
  it('Should return corrent date and time in LLL format', () => {
    assert.strictEqual('June 27, 2562 2:15 AM', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'LLL'))
  })
  it('Should return correct date without time in LLL format', () => {
    assert.strictEqual('June 27, 2562 12:00 AM', toBuddhistYear(moment('2019-06-27'), 'LLL'))
  })
  it('Should return corrent date and time in lll format', () => {
    assert.strictEqual('Jun 27, 2562 2:15 AM', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'lll'))
  })
  it('Should return correct date without time in lll format', () => {
    assert.strictEqual('Jun 27, 2562 12:00 AM', toBuddhistYear(moment('2019-06-27'), 'lll'))
  })
  it('Should return corrent date and time with LL format', () => {
    assert.strictEqual('June 27, 2562', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'LL'))
  })
  it('Should return correct date without time in LL format', () => {
    assert.strictEqual('June 27, 2562', toBuddhistYear(moment('2019-06-27'), 'LL'))
  })
  it('Should return corrent date and time in ll format', () => {
    assert.strictEqual('Jun 27, 2562', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'll'))
  })
  it('Should return correct date without time in ll format', () => {
    assert.strictEqual('Jun 27, 2562', toBuddhistYear(moment('2019-06-27'), 'll'))
  })
  it('Should return corrent date and time in L format', () => {
    assert.strictEqual('06/27/2562', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'L'))
  })
  it('Should return correct date without time in L format', () => {
    assert.strictEqual('06/27/2562', toBuddhistYear(moment('2019-06-27'), 'L'))
  })
  it('Should return corrent date and time in l format', () => {
    assert.strictEqual('6/27/2562', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'l'))
  })
  it('Should return correct date without time in l format', () => {
    assert.strictEqual('6/27/2562', toBuddhistYear(moment('2019-06-27'), 'l'))
  })
  it('Should return corrent date and time in MM/DD/YYYY format', () => {
    assert.strictEqual('06/27/2562', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'MM/DD/YYYY'))
  })
  it('Should return correct date without time in MM/DD/YYYY format', () => {
    assert.strictEqual('06/27/2562', toBuddhistYear(moment('2019-06-27'), 'MM/DD/YYYY'))
  })
  it('Should return corrent date and time in MM/DD/YY format', () => {
    assert.strictEqual('06/27/62', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'MM/DD/YY'))
  })
  it('Should return correct date without time in MM/DD/YY format', () => {
    assert.strictEqual('06/27/62', toBuddhistYear(moment('2019-06-27'), 'MM/DD/YY'))
  })
  it('Should return corrent date and time in MM/DD/Y format', () => {
    assert.strictEqual('06/27/2562', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'MM/DD/Y'))
  })
  it('Should return correct date without time in MM/DD/Y format', () => {
    assert.strictEqual('06/27/2562', toBuddhistYear(moment('2019-06-27'), 'MM/DD/Y'))
  })
  it('Should return correct date without time in YYYY-MM-DDTHH:mm:ss.sssZ format', () => {
    assert.strictEqual('2562-06-27T02:15:07.077+07:00', toBuddhistYear(moment('2019-06-27T02:15:07+07:00'), 'YYYY-MM-DDTHH:mm:ss.sssZ'))
  })
  it('Should return corrent date and time in MM/DD/Y format and leap day', () => {
    assert.strictEqual('02/29/2563', toBuddhistYear(moment('2020-02-29:15:07+07:00'), 'MM/DD/Y'))
  })
  it('Should return correct date without time in MM/DD/Y format and leap day', () => {
    assert.strictEqual('02/29/2563', toBuddhistYear(moment('2020-02-29'), 'MM/DD/Y'))
  })
  it('Should return correct date without time in YYYY-MM-DDTHH:mm:ss.sssZ format and leap day', () => {
    assert.strictEqual('2563-02-29T02:15:07.077+07:00', toBuddhistYear(moment('2020-02-29T02:15:07+07:00'), 'YYYY-MM-DDTHH:mm:ss.sssZ'))
  })
})

@ekaluckc ตามที่คุณ @ToeiKanta บอกเลยครับ ผมไม่ได้เอา 543 บวกเข้าไปในปีตรงๆครับ แต่ใช้วิธี Replace ใน String Year แทน

เพิ่มเทสสำหรับ Leap Days เข้าไปให้แล้วครับ

รับทราบครับ จริงด้วยครับ สุดยอด ขอบคุณมากครับ ขออภัยที่อ่าน code เร็วไปหน่อยครับ