legalId

legalId — Iranian Legal ID (شناسه ملی حقوقی) validation

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

Public export

verifyIranianLegalId(legalId: string | number): boolean | undefined

Behaviour

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

verifyIranianLegalId("10380284790");      // true
verifyIranianLegalId(10380284790);         // true — number accepted
verifyIranianLegalId("00000000000");      // false (all zeros)
verifyIranianLegalId(undefined as any);   // undefined

Algorithm

1. Falsy input → undefined.
2. Stringify; length must be ≥ 11.
3. Reject if parseInt(legalId) is 0 (all-zero string).
4. Reject if the middle 6 digits (slice(3, 9)) are all zero.
5. Check digit:

   d  = digit[9] + 2
   z  = [29, 27, 23, 19, 17]   // 5-period coefficient vector
   sum = Σ (d + digit[i]) * z[i mod 5]  for i in 0..9
   sum = sum mod 11
   if (sum === 10) sum = 0
   valid = digit[10] === sum
   

Quirks

• Length check is < 11, not === 11. Inputs longer than 11 are accepted; the algorithm slices at fixed indices, so longer strings can still validate. If you need strict 11-digit input, check String(input).length === 11 separately.
• Persian/Arabic digit input is NOT normalized. parseInt("۱۰۳۸۰۲۸۴۷۹۰") is NaN. Normalize with autoConvertDigitsToEN first.
• Return type is boolean | undefined. undefined for falsy input, boolean after the check runs. Don't truthy-test the result.

When NOT to use

• For Iranian personal IDs (10 digits) — use verifyIranianNationalId. The algorithms are different.

References

• Tests: test/verifyIranianLegalId.spec.ts
• Algorithm reference: http://www.aliarash.com/article/shenasameli/shenasa_meli.htm (linked in JSDoc)
• Related: nationalId skill (the personal-ID counterpart)