verifyCardNumber

verifyCardNumber — Iranian card-number validation

import { verifyCardNumber } from "@persian-tools/persian-tools";
// CommonJS
const { verifyCardNumber } = require("@persian-tools/persian-tools");

Public export

verifyCardNumber(digits: number | string): boolean | undefined

Behaviour

import { verifyCardNumber } from "@persian-tools/persian-tools";

verifyCardNumber("6037701689095443");     // true
verifyCardNumber("6037 7016 8909 5443");   // true (whitespace stripped first)
verifyCardNumber(6037701689095443);        // true (number accepted)
verifyCardNumber("4111111111111111");      // false (Luhn-valid but non-Iranian BIN)
verifyCardNumber("0000000000000000");      // false (all-zero middle blocks)
verifyCardNumber(null as any);             // undefined

Algorithm — two-stage validation

1. Falsy → undefined. Truthy check before anything else.
2. Whitespace strip + format check. String(input).replace(/\s/g, "").trim() must match /^\d{16}$/. Anything else → false.
3. All-zero sub-block check. Reject if digits.slice(1,11) is all zero, OR digits.slice(10,16) is all zero.
4. BIN check. The 6-digit BIN prefix (slice(0,6)) must be in iranianBankPrefixes (src/modules/verifyCardNumber/constants.ts). Non-Iranian Luhn-valid cards (e.g. test Visa numbers like 4111...) are rejected here.
5. Luhn checksum. Standard mod-10, doubling every second digit from the right; if doubled > 9 subtract 9. Sum % 10 must equal 0.

Quirks

• Persian/Arabic digit input is NOT normalized. "۶۰۳۷۷۰۱۶۸۹۰۹۵۴۴۳" fails the /^\d{16}$/ step → false. Run autoConvertDigitsToEN first if input may contain them.
• Return type is boolean | undefined. undefined for falsy input, boolean after the algorithm runs. Use === true, not truthy-check.
• Non-Iranian cards are rejected even if Luhn-valid. This is intentional. If you need generic Luhn validation (not BIN-gated), use a third-party Luhn library — verifyCardNumber is specifically Iranian.

Companion functions

For richer card workflows in the same family:

• getBankNameFromCardNumber — given a card number, return the issuing bank's Persian name. See its skill.
• extractCardNumber — pull card numbers out of free-text input. See extractCardNumbers skill.

Pipeline for free-text input

import {
  autoConvertDigitsToEN,
  verifyCardNumber,
  getBankNameFromCardNumber,
} from "@persian-tools/persian-tools";

const check = (raw: string) => {
  const norm = autoConvertDigitsToEN(raw.trim());
  const valid = verifyCardNumber(norm) === true;
  return { valid, bank: valid ? getBankNameFromCardNumber(norm) : null };
};

Common pitfalls

• Adding new BINs: edit iranianBankPrefixes AND getBankNameFromCardNumber's cardBank table together. Out-of-sync tables are a recurring source of "validator accepts the card but lookup says unknown bank" bugs.
• For test fixtures, generate cards by combining a known BIN (from iranianBankPrefixes) with a Luhn-valid tail. Don't paste real card numbers.

References

• Tests: test/verifyCardNumber.spec.ts
• Related: getBankNameFromCardNumber, extractCardNumbers skills
• Algorithm: standard Luhn (mod-10) + Iranian BIN whitelist