se-panfilov/jsvat

import { Country } from '../jsvat';

export const serbia: Country = {
  name: 'Serbia',
  codes: ['RS', 'SRB', '688'],
  calcFn: (vat: string): boolean => {
    // Checks the check digits of a Serbian VAT number using ISO 7064, MOD 11-10 for check digit.

    let product = 10;
    let sum = 0;

    for (let i = 0; i < 8; i++) {
      // Extract the next digit and implement the algorithm
      sum = (Number(vat.charAt(i)) + product) % 10;
      if (sum === 0) {
        sum = 10;
      }
      product = (2 * sum) % 11;
    }

    // Now check that we have the right check digit
    const expect = 1;
    const checkDigit = (product + Number(vat.slice(8, 9))) % 10;
    return checkDigit === expect;
  },
  rules: {
    multipliers: {},
    regex: [/^(RS)(\d{9})$/]
  }
};