Equivalent to PHP function number_format in Javascript

index.ts

const assert = require('assert');
const numberFormat = require('./numberFormat');

assert.strictEqual(
  numberFormat(132323232320.321, 2, ',', '.'),
  '132.323.232.320,32'
);
assert.strictEqual(
  numberFormat(10.22),
  '10.22'
);
assert.strictEqual(
  numberFormat(100),
  '100'
);
assert.strictEqual(
  numberFormat(1000, 2, ',', '.'),
  '1.000,00'
);

assert.strictEqual(
numberFormat(95**12, 2),
'540,360,087,662,636,990,201,856'
);

assert.strictEqual(
numberFormat(123e5, 2),
'12,300,000.00'
);

assert.strictEqual(
numberFormat(123e5),
'12,300,000'
);

assert.strictEqual(
numberFormat(123e-5),
'0.00'
);

assert.strictEqual(
numberFormat(123e-15),
'0'
);

assert.strictEqual(
numberFormat(123e-15, 15),
'0.000000000000123'
);

numberFormat.js

const splitThousands = (number) => (dec_point, thousands_point) => {
  const splitNum = number.toString().split(dec_point);
  splitNum[0] = splitNum[0].replace(/\B(?=(\d{3})+(?!\d))/g, thousands_point);
  return splitNum.join(dec_point);
};

const isBigNumber = (number) => number.toString().includes("e");

const isBigFloat = (number) => number.toString().includes("-");

const calcTrailing = (dec, len) => Number(dec) + 2 - len;

const handleBigFloats = (number, decimals) => {
  if (!decimals) {
    return "0";
  }

  const [numbers, dec] = number.toString().replace(".", "").split("e-");
  const trailingZeros = calcTrailing(dec, numbers.length);
  const res = `${"0.".padEnd(trailingZeros + 2, "0")}${numbers}`;

  return decimals ? res.substring(0, 2) + res.substring(2, decimals + 2) : res;
};

const handleBigNumbers = (number, decimals, dec_point, thousands_point) => {
  if (isBigFloat(number)) {
    return handleBigFloats(number, decimals);
  }

  return splitThousands(BigInt(number))(dec_point, thousands_point);
};

function handleFiniteNumbers(number, decimals, dec_point, thousands_point) {
  if (!isFinite(number)) {
    throw new TypeError("number is not finite number");
  }

  if (!decimals) {
    const len = number.toString().split(".").length;
    decimals = len > 1 ? len : 0;
  }

  return splitThousands(
    parseFloat(number).toFixed(decimals).replace(".", dec_point)
  )(dec_point, thousands_point);
}

const numberFormat = (
  number,
  decimals,
  dec_point = ".",
  thousands_point = ","
) => {
  if (number == null || typeof number !== "number") {
    throw new TypeError("number is not valid");
  }

  if (isBigNumber(number)) {
    return handleBigNumbers(number, decimals, dec_point, thousands_point);
  }

  return handleFiniteNumbers(number, decimals, dec_point, thousands_point);
};

module.exports = numberFormat;