class numberFormatter {
  static get numbers() {
    return (this.__testNumbers__ = [
      -123456789012,
      -12345678901,
      -1234567890,
      -123456789,
      -12345678,
      -1234567,
      -123456,
      -12345,
      -1234,
      -123,
      -12,
      -1,
      0,
      1,
      12,
      123,
      1234,
      12345,
      123456,
      1234567,
      12345678,
      123456789,
      1234567890,
      12345678901,
      123456789012
    ]);
  }

  static format() {
    this.numbers.forEach(number => {
      if (typeof number !== "number") throw TypeError("Not a number");

      let isNegative = number < 0;
      let formattedNumber = isNegative ? "-" : "";
      let digits = number
        .toString()
        .replace("-", "")
        .split("")
        .reverse();

      for (let index = digits.length - 1; index >= 0; index--) {
        let digit = digits[index];
        let addTrailingComma = index > 0 && index % 3 === 0;

        formattedNumber += addTrailingComma ? `${digit},` : digit;
      }

      console.log(formattedNumber);
    });
  }
}