Currency Formatter for TextInput

FormatCurrencyForTextInput.ts

enum Currency {
  IDR = "IDR",
  USD = "USD",
}

const separator: Record<Currency, string> = {
  IDR: ".",
  USD: ",",
};

const extractNumbersFromString = (str: string) => str.replace(/\D/g, "");

const reverseString = (str: string) => {
  const stringChars = str.split("");
  let store: string[] = [];

  stringChars.forEach((stringChar, index) => {
    store[stringChars.length - 1 - index] = stringChar;
  });

  return store.join("");
};

const formatCurrency = (value: string, currency: Currency = Currency.IDR) => {
  const selectedSeparator = separator[currency];

  // 1. Get numbers extracted from string
  const valueNumber = Number(extractNumbersFromString(value));

  // 2. Remove 0
  if (valueNumber === 0) {
    return "";
  }

  // 3. Format Value
  const stringValue = String(valueNumber);

  // 4. Reverse stringValue
  const reversedStringValue = reverseString(stringValue);

  // 5. For every 3 chars add comma
  const result: string[] = [];

  for (let i = 0; i < reversedStringValue.length; i += 3) {
    result.push(reversedStringValue.substring(i, i + 3));
  }

  return reverseString(result.join(selectedSeparator));
};