A javascript function to parse a Federal Firearms License (FFL) number

parseFFL.js

/**
 * Parses the FFL number and extracts relevant information.
 *
 * @param {string} fflNumber - The FFL number to parse.
 * @returns {object} - An object containing the parsed FFL information or an error object.
 *                     If parsing is successful, the object will have the following properties:
 *                     - ffl_number: The full FFL number.
 *                     - region: The region of the FFL.
 *                     - irs_district: The IRS district of the FFL.
 *                     - fips_code: The FIPS code of the FFL.
 *                     - license_type: The type of license.
 *                     - expiration_date: The expiration date of the FFL.
 *                     - unique_code: The unique code of the FFL.
 *                     If any information cannot be calculated, an error object will be returned.
 *                     The error object will have the following properties:
 *                     - error: A descriptive error message.
 *                     - ffl_number: The full FFL number (optional, if available).
 *
 * @author Stephen Feather
 * @copyright Copyright (c) 2023
 */
function parseFFLNumber(fflNumber) {
  const regions = {
    1: 'Region 1: Southeast',
    3: 'Region 3: Midwest',
    4: 'Region 4: Central',
    5: 'Region 5: Southwest',
    6: 'Region 6: North Atlantic',
    8: 'Region 8: Mid Atlantic',
    9: 'Region 9: Western'
  };

  const months = {
    A: 'January',
    B: 'February',
    C: 'March',
    D: 'April',
    E: 'May',
    F: 'June',
    G: 'July',
    H: 'August',
    J: 'September',
    K: 'October',
    L: 'November',
    M: 'December'
  };

  const licenseTypes = {
    1: 'Type 01: Firearm Dealer/Gunsmith',
    2: 'Type 02: Pawnbroker',
    3: 'Type 03: Collector',
    6: 'Type 06: Manufacturer of Ammunition',
    7: 'Type 07: Manufacturer of Firearms',
    8: 'Type 08: Importer of Firearms',
    9: 'Type 09: Dealer of "Destructive Devices"',
    10: 'Type 10: Manufacturer of "Destructive Devices"',
    11: 'Type 11: Importer of "Destructive Devices"'
  };

  const fflInfo = {};

  // First section: FFL Number
  fflInfo.ffl_number = fflNumber;

  // Second section: Region
  const regionDigit = parseInt(fflNumber[0]);
  if (regions[regionDigit]) {
    fflInfo.region = regions[regionDigit];
  } else {
    return {
      error: 'Invalid Region',
      ffl_number: fflNumber
    };
  }

  // Third section: IRS district
  fflInfo.irs_district = parseInt(fflNumber.substr(2, 2));

  // Fourth section: FIPS code
  fflInfo.fips_code = fflNumber.substr(5, 3);

  // Fifth section: License type
  const licenseTypeDigit = parseInt(fflNumber.substr(9, 2));
  if (licenseTypes[licenseTypeDigit]) {
    fflInfo.license_type = licenseTypes[licenseTypeDigit];
  } else {
    return {
      error: 'Invalid License Type',
      ffl_number: fflNumber
    };
  }

  // Sixth section: Expiration date
  const yearDigit = parseInt(fflNumber[12]);
  const monthLetter = fflNumber[13];
  const currentYear = new Date().getFullYear();
  const yearPrefix = currentYear - (currentYear % 10);
  const year = yearPrefix + yearDigit;
  if (months[monthLetter]) {
    fflInfo.expiration_date = months[monthLetter] + ' ' + year;
  } else {
    return {
      error: 'Invalid Expiration Month',
      ffl_number: fflNumber
    };
  }

  // Seventh section: Unique code
  fflInfo.unique_code = fflNumber.substr(15);

  return fflInfo;
}