index.js

"use strict"

/* Setup comma and leading zeros */

const commaFormatter = (nominal, settings) => {
  if (!nominal) {
    nominal = settings.replaceZeroDecimals ? '-' : '00'
  } else {
    const diffLength = settings.floatingPoint - nominal.length
    if (diffLength > 0) {
      for (let i = 0; i < settings.floatingPoint - nominal.length; i++) {
        nominal += '0'
      }
    } else if (diffLength < 0) {
      nominal = nominal.slice(0, diffLength)
    }
  }
  return nominal
}

/* Place dots every three digit start from the most right */

const dotsFormatter = (target, settings) => {
  const angka = target.split('.')
  const size  = angka[0].length
  let result  = angka[0].split('')

  for (let i = size - 1; i >= 0; i--) {
    if ((size - i) % 3 === 0 && i > 0) {
      result[i] = settings.dot + result[i]
    }
  }

  const angkaDepan = result.join('')

  if (settings.removeZeroDecimals && !angka[1]) {
    return angkaDepan;
  } else {
    const angkaBelakang = commaFormatter(angka[1] || null, settings)
    return settings.floatingPoint > 0
      ? angkaDepan + settings.decimal + angkaBelakang
      : angkaDepan
  }
}

/* Append or prepend currency symbol based on formal / informal use */

const symbolFormatter = (nominal, settings) => {
  if (settings.symbol === 'Rp') {
    nominal = settings.formal ? 'Rp' + nominal : 'Rp ' + nominal
  } else if (settings.symbol === 'IDR') {
    nominal = settings.formal ? nominal + ' IDR' : 'IDR ' + nominal
  }
  return nominal
}

/* Take 1-3 digit from the left, round the rest with comma, append the unit name */

const unitFormatter = (target, settings) => {
  const units = settings.longUnit
    ? ['ribu', 'juta', 'milyar', 'triliun'] 
    : [settings.k ? 'k' : 'rb', 'jt', 'M', 'T']
  const unitIndex = Math.ceil(target.length / 3) - 2

  let nominal = null

  if (unitIndex >= 0 && unitIndex < 4) {
    let unit = units[unitIndex]
    if (settings.spaceBeforeUnit) unit = ' ' + unit

    const modDigit = target.length % 3
    const sliceIndex = modDigit === 0 ? 3 : modDigit

    nominal = target.substr(0, sliceIndex)
    nominal += (unitIndex >= 0 && settings.floatingPoint > 0 ? settings.decimal : '')
      + target.substr(sliceIndex, settings.floatingPoint)
      + unit
  } 
  else {
    nominal = dotsFormatter(target, settings)
  }

  return nominal
}

const defaultSettings = {
  symbol: 'Rp', // ['Rp', 'IDR', null]
  formal: true,
  dot: '.',
  decimal: ',',
  floatingPoint: 2,
  replaceZeroDecimals: false, // Rp100.000,-
  removeZeroDecimals: false,
  k: false, // k
  useUnit: false, // rb, jt, M, T
  longUnit: false, // ribu, juta, milyar, triliun
  spaceBeforeUnit: false
}

module.exports = function toRupiah(target, settings={}) {
  target = (typeof target !== "string") ? target.toString() : target
  settings = Object.assign({}, defaultSettings, settings)

  return settings.useUnit
    ? symbolFormatter(unitFormatter(target, settings), settings)
    : symbolFormatter(dotsFormatter(target, settings), settings)
}