A TypeScript function to convert numbers to Bengali words.

number-to-bengali-words.ts

/**
 * @license ISC License (ISC)
 * 
 * Copyright (c) 2021 Maruf Hassan.
 * 
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, 
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 * 
 * GitHub Repository:
 * [number-to-bengali-words](https://github.com/maruf571/number-to-bengali-words)
 */
const NEGATIVE = "ঋণাত্মক";
const DECIMAL = " দশমিক";
const ONE_HUNDRED = 100;
const ONE_THOUSAND = 1000;
const ONE_LAKH = 100000;
const ONE_CRORE = 10000000;

const number2WordMap: Record<number, string> = {
  0 : "শূন্য",
  1 : "এক", 
  2 : "দুই", 
  3 : "তিন", 
  4 : "চার", 
  5 : "পাঁচ", 
  6 : "ছয়", 
  7 : "সাত", 
  8 : "আট", 
  9 : "নয়", 
  10 : "দশ", 
  11 : "এগারো", 
  12 : "বারো", 
  13 : "তেরো", 
  14 : "চৌদ্দ", 
  15 : "পনের", 
  16 : "ষোল", 
  17 : "সতের", 
  18 : "আঠার", 
  19 : "উনিশ", 
  20 : "বিশ", 
  21 : "একুশ", 
  22 : "বাইশ", 
  23 : "তেইশ", 
  24 : "চব্বিশ", 
  25 : "পঁচিশ", 
  26 : "ছাব্বিশ", 
  27 : "সাতাশ", 
  28 : "আটাশ", 
  29 : "ঊনত্রিশ", 
  30 : "ত্রিশ", 
  31 : "একত্রিশ", 
  32 : "বত্রিশ", 
  33 : "তেত্রিশ", 
  34 : "চৌত্রিশ", 
  35 : "পঁয়ত্রিশ", 
  36 : "ছত্রিশ", 
  37 : "সাইত্রিশ", 
  38 : "আটত্রিশ", 
  39 : "ঊনচল্লিশ", 
  40 : "চল্লিশ", 
  41 : "একচল্লিশ", 
  42 : "বিয়াল্লিশ", 
  43 : "তেতাল্লিশ", 
  44 : "চুয়াল্লিশ", 
  45 : "পঁয়তাল্লিশ", 
  46 : "ছিচল্লিশ", 
  47 : "সাতচল্লিশ",
  48 : "আটচল্লিশ", 
  49 : "ঊনপঞ্চাশ", 
  50 : "পঞ্চাশ", 
  51 : "একান্ন", 
  52 : "বাহান্ন", 
  53 : "তেপ্পান্ন", 
  54 : "চুয়ান্ন", 
  55 : "পঞ্চান্ন", 
  56 : "ছাপ্পান্ন", 
  57 : "সাতান্ন", 
  58 : "আটান্ন", 
  59 : "ঊনষাট", 
  60 : "ষাট", 
  61 : "একষট্টি", 
  62 : "বাষট্টি", 
  63 : "তেষট্টি", 
  64 : "চৌষট্টি", 
  65 : "পঁয়ষট্টি", 
  66 : "ছেষট্টি", 
  67 : "সাতষট্টি", 
  68 : "আটষট্টি", 
  69 : "ঊনসত্তর", 
  70 : "সত্তর", 
  71 : "একাত্তর", 
  72 : "বাহাত্তর", 
  73 : "তেহাত্তর", 
  74 : "চুয়াত্তর", 
  75 : "পঁচাত্তর",
  76 : "ছিয়াত্তর", 
  77 : "সাতাত্তর", 
  78 : "আটাত্তর", 
  79 : "ঊনআশি", 
  80 : "আশি", 
  81 : "একাশি", 
  82 : "বিরাশি", 
  83 : "তিরাশি", 
  84 : "চুরাশি", 
  85 : "পঁচাশি", 
  86 : "ছিয়াশি", 
  87 : "সাতাশি", 
  88 : "আটাশি", 
  89 : "উননব্বই", 
  90 : "নব্বই", 
  91 : "একানব্বই", 
  92 : "বিরানব্বই", 
  93 : "তিরানব্বই", 
  94 : "চুরানব্বই", 
  95 : "পঁচানব্বই", 
  96 : "ছিয়ানব্বই", 
  97 : "সাতানব্বই", 
  98 : "আটানব্বই", 
  99 : "নিরানব্বই", 
  100 : "শত", 
  1000 : "হাজার", 
  100000 : "লক্ষ", 
  10000000 : "কোটি",
};

/**
 * This function converts a number to Bengali words. Thanks to 
 * [Maruf Hassan](https://github.com/maruf571/) for his solution.
 * 
 * Converted to TypeScript by
 * [Shadman Chowdhury](https://github.com/codesfromshad/).
 * 
 * @param number - A number to convert to Bengali words.
 * @returns A string of Bengali words.
 * 
 * @example
 * //Convert an integer to Bengali words
 * console.log(toBengaliWords(123)); // Outputs: "একশ তেইশ"
 *
 * // Convert a floating-point number to Bengali words
 * console.log(toBengaliWords(45.67)); // Outputs: "পঁয়তাল্লিশ দশমিক ছয় সাত"
 *
 * // Convert a negative number to Bengali words
 * console.log(toBengaliWords(-200)); // Outputs: "ঋণাত্মক দুইশ"
 */
const numberToBengaliWords = function(
  number: number, 
) {
  let words = "";

  if (!isFinite(number)) {
    throw new TypeError(
      "Not a finite number: " + number + " (" + typeof number + ")"
    );
  }
  if (!isSafeNumber(number)) {
    throw new RangeError(
      "Input is not a safe number, it’s either too large or too small."
    );
  }

  const num = parseInt(number.toString(), 10);
  words = generateWords(num);

  if (!isInt(number)) {
    const point = number.toString().split(".")[1];
    if (point) {
      words += DECIMAL;
      for (const digit of point) {
        words += " " + number2WordMap[+digit];
      }
    }
  }

  return words;
};


function generateWords(number: number, words?: string[]): string {

  let remainder = 0;
  let word = "";

  if(number === 0){
    return !words ? (number2WordMap[0] ?? "শূন্য") : words.join(" ").replace(/,$/, "");
  }

  if (!words) {
    words = [];
  }

  if (number < 0) {
    words.push(NEGATIVE);
    number = Math.abs(number);
  }

  if (number < ONE_HUNDRED) {
    remainder = 0;
    word = number2WordMap[number] ?? "[unknown]";
  } 
  else if (number < ONE_THOUSAND) {
    remainder = number % ONE_HUNDRED;
    word = (number2WordMap[Math.floor(number / ONE_HUNDRED)] ?? "[unknown]") + number2WordMap[ONE_HUNDRED];
  }
  else if (number < ONE_LAKH) {
    remainder = number % ONE_THOUSAND;
    word = number2WordMap[Math.floor(number / ONE_THOUSAND)] + " " + number2WordMap[ONE_THOUSAND];
  }
  else if (number < ONE_CRORE) {
    remainder = number % ONE_LAKH;
    word = number2WordMap[Math.floor(number/ONE_LAKH)] + " " + number2WordMap[ONE_LAKH];
  } else {
    remainder = number % ONE_CRORE;
    word = generateWords(Math.floor(number / ONE_CRORE)) + " " + number2WordMap[ONE_CRORE];
  }

  words.push(word);

  return generateWords(remainder, words);
}


function isFinite(value: number) {
  return !(typeof value !== "number" || value !== value || value === Infinity || value === -Infinity);
}

const MAX_SAFE_INTEGER = 9007199254740991;
function isSafeNumber(value: number) {
  return typeof value === "number" && Math.abs(value) <= MAX_SAFE_INTEGER;
}

function isInt(n: number) {
  return n % 1 === 0;
}

export default numberToBengaliWords;