amount-in-words/src/index.ts

Convert amount in words

export enum CountryCodes {
  IND = "IND",
  USA = "USA",
  GBR = "GBR"
}

export class AmountToWords {
  private first = [
    "",
    "One ",
    "Two ",
    "Three ",
    "Four ",
    "Five ",
    "Six ",
    "Seven ",
    "Eight ",
    "Nine ",
    "Ten ",
    "Eleven ",
    "Twelve ",
    "Thirteen ",
    "Fourteen ",
    "Fifteen ",
    "Sixteen ",
    "Seventeen ",
    "Eighteen ",
    "Nineteen ",
  ];
  private tens = [
    "",
    "",
    "Twenty ",
    "Thirty ",
    "Forty ",
    "Fifty ",
    "Sixty ",
    "Seventy ",
    "Eighty ",
    "Ninety ",
  ];
  private numSys: { [currencyCode: string]: string[] } = {
    usNumSys: [
      "",
      "Hundred ",
      "Thousand ",
      "Million ",
      "Billion ",
      "Trillion ",
    ],
    inNumSys: ["", "Hundred ", "Thousand ", "Lakh ", "Crore "],
  };
  private curCodes: { [countryCode: string]: string[] } = {
    IND: ["Rupee", "Paisa", "Paise", "₹", "inNumSys"],
    USA: ["Dollar", "Cent", "Cents", "$", "usNumSys"],
    GBR: ["Pound", "Pence", "Pence", "£", "usNumSys"],
  };

  public toWords = (amount: string | number, countryCode: string = "IND") => {
    // console.log(num);
    const numSys = this.numSys[this.getNumSys(countryCode)];
    const nStr = amount.toString().split(".");
    // Remove any other characters than numbers
    const wholeStr = Number(nStr[0].replace(/[^a-z\d\s]+/gi, ""));
    const decimalStr = nStr.length > 1 ? Number(nStr[1]) : 0;
    const wholeStrPart =
      this.getNumSys(countryCode) === "inNumSys"
        ? this.convert(wholeStr, numSys).trim()
        : this.convertInUS(wholeStr, numSys).trim();
    const decimalPart = this.convert(decimalStr, numSys).trim();
    let valueInStr =
      wholeStrPart.length > 0
        ? `${wholeStrPart} ${this.getCurrencyWhole(countryCode, wholeStr)}`
        : `Zero ${this.getCurrencyWhole(countryCode, wholeStr)}`;
    valueInStr =
      decimalPart.length > 0
        ? `${valueInStr} And ${decimalPart} ${this.getCurrencyChange(
            countryCode,
            decimalStr
          )}`
        : valueInStr;
    // console.log(valueInStr);
    return valueInStr;
  };

  private getCurrencyWhole = (
    countryCode: string = "IND",
    amount: number = 0
  ) => {
    const cur = this.curCodes[countryCode]
      ? this.curCodes[countryCode][0]
      : this.curCodes["IND"][0];
    if (amount > 1) return cur + "s";
    else return cur;
  };

  private getCurrencyChange = (countryCode: string, amount: number = 0) => {
    if (amount > 1)
      return this.curCodes[countryCode]
        ? this.curCodes[countryCode][2]
        : this.curCodes["IND"][2];
    else
      return this.curCodes[countryCode]
        ? this.curCodes[countryCode][1]
        : this.curCodes["IND"][1];
  };

  private getCurrencySymbol = (countryCode: string) => {
    return this.curCodes[countryCode]
      ? this.curCodes[countryCode][2]
      : this.curCodes["IND"][2];
  };

  private getNumSys = (countryCode: string) => {
    return this.curCodes[countryCode]
      ? this.curCodes[countryCode][4]
      : this.curCodes["IND"][4];
  };

  private convert = (num: number | string, numSys: string[]) => {
    const numStr = num.toString().split("");
    const finalStr = [];
    while (numStr.length > 0) {
      for (let i = 0; i < numSys.length - 1; ++i) {
        if (i === 1)
          finalStr.unshift(this.getUnits(numStr.splice(-1), numSys, i));
        else finalStr.unshift(this.getUnits(numStr.splice(-2), numSys, i));
      }
      if (numStr.length > 0) finalStr.unshift(...numSys.slice(-1));
    }
    return finalStr.join("");
  };

  private convertInUS = (num: number | string, numSys: string[]) => {
    const numStr = num.toString().split("");
    const finalStr = [];
    while (numStr.length > 0) {
      // console.log(numSys.length);
      for (let i = 0, l = numSys.length * 2 - 1; i < l; ++i) {
        // console.log(numStr, i, (i/2)+1);
        if (i === 0)
          finalStr.unshift(this.getUnits(numStr.splice(-2), numSys, 0));
        else if (i % 2 === 1)
          finalStr.unshift(this.getUnits(numStr.splice(-1), numSys, 1));
        else {
          finalStr.unshift(this.getUnits(numStr.splice(-2), numSys, i / 2 + 1));
        }
      }
      if (numStr.length > 0) finalStr.unshift(...numSys.slice(-1));
      else break;
    }
    return finalStr.join("");
  };

  private getUnits = (
    lastTwo: string[],
    numSys: string[],
    place?: number
  ): string => {
    if (!lastTwo || lastTwo.length === 0) return "";
    let numInStr = "";
    if (this.first[Number(lastTwo.join(""))])
      numInStr = this.first[Number(lastTwo.join(""))];
    else
      numInStr = `${this.tens[Number(lastTwo.shift())]}${this.getUnits(
        lastTwo.slice(-1),
        numSys
      )}`;
    if (numInStr && place) numInStr = `${numInStr}${numSys[place] ?? ""}`;
    return numInStr;
  };
}