currency mask

currency.js

const NUMBER_TO_DEFINE_DECIMAL_SEPARATOR_AND_CURRENCY = 1.1;

function getDecimalSeparatorByLocale(locale) {
  return new Intl.NumberFormat(locale)
    .format(NUMBER_TO_DEFINE_DECIMAL_SEPARATOR_AND_CURRENCY)
    .replace(/\d/g, "");
}

function getThousandSeparatorByDecimalSeparator(decimalSeparator) {
  if (decimalSeparator === ".") {
    return ",";
  }
  return ".";
}

export function normalizeInitialValueByPrecision(
  currentValue = "0",
  decimalPlaces = 0
) {
  if (decimalPlaces === 0) {
    return currentValue;
  }
  if (!String(currentValue).split(/,|\./)[1]) {
    return String(currentValue) + ".".padEnd(decimalPlaces + 1, "0");
  }
  let newValue = String(currentValue);
  while (newValue.split(/,|\./)[1].length < decimalPlaces) {
    newValue += "0";
  }
  return newValue;
}

export function applyMask(
  currentValue = "",
  precision = 0,
  locale = "en",
  enabledThousandSeparator = false
) {
  const decimalSeparator = getDecimalSeparatorByLocale(locale);

  const thousandSeparator = enabledThousandSeparator
    ? getThousandSeparatorByDecimalSeparator(decimalSeparator)
    : "";
  // extract digits. if no digits, fill in a zero.
  const digits = String(currentValue).match(/\d/g) || ["0"];

  // remove leading zeros
  while (digits.length > 1 && digits[0] === "0") {
    digits.shift();
  }
  // zero-pad a input
  while (digits.length <= precision) {
    digits.unshift("0");
  }

  if (enabledThousandSeparator) {
    for (let x = digits.length - precision - 3; x > 0; x = x - 3) {
      digits.splice(x, 0, thousandSeparator);
    }
  }
  if (precision > 0) {
    // add the decimal separator
    digits.splice(digits.length - precision, 0, decimalSeparator);
  }

  const newValue = digits.join("");

  return {
    value: newValue
      .replace(RegExp(thousandSeparator, "g"), "")
      .replace(",", "."),
    maskedValue: newValue
  };
}