masked-input-utils-ts/src/index.ts

Reusable masking utility for PAN, Aadhar, CVV, Mobile Numbers, Email with TypeScript support

export function maskPAN(pan: string, showPartial = true): string {
  if (!/^[A-Z]{5}[0-9]{4}[A-Z]{1}$/.test(pan)) return 'Invalid PAN';
  return showPartial ? `${pan.slice(0, 2)}*****${pan.slice(-3)}` : '***********';
}

export function maskAadhar(aadhar: string): string {
  const cleaned = aadhar.replace(/\D/g, '');
  if (cleaned.length !== 12) return 'Invalid Aadhar';
  return `XXXX-XXXX-${cleaned.slice(-4)}`;
}

export function maskCVV(cvv: string): string {
  return /^\d{3,4}$/.test(cvv) ? '*'.repeat(cvv.length) : 'Invalid CVV';
}

export function maskMobile(mobile: string): string {
  const cleaned = mobile.replace(/\D/g, '');
  if (cleaned.length !== 10) return 'Invalid Mobile Number';
  return `${cleaned.slice(0, 2)}******${cleaned.slice(-2)}`;
}

export function maskEmail(email: string): string {
  const [user, domain] = email.split('@');
  if (!user || !domain) return 'Invalid Email';
  return `${user[0]}${'*'.repeat(user.length - 1)}@${domain}`;
}

export function maskGeneric(
  str: string,
  options: { unmaskedStart: number; unmaskedEnd: number; maskChar?: string }
): string {
  const { unmaskedStart, unmaskedEnd, maskChar = '*' } = options;
  if (!str || str.length < unmaskedStart + unmaskedEnd) return maskChar.repeat(str.length);
  return (
    str.slice(0, unmaskedStart) +
    maskChar.repeat(str.length - unmaskedStart - unmaskedEnd) +
    str.slice(-unmaskedEnd)
  );
}