Converts state fips codes into postal codes and back again.

fips2Postal.js

/**
* Available Exports:
* @export {array}     postalFipsList  – list of state objects with 'FIPS' and 'postal' keys
* @export {object}    fipsByPostal    – dictionary with postal codes as keys and corresponding FIPS code as value
* @export {object}    postalByFips    – dictionary with FIPS codes as keys and corresponding postal code as value
* @export {function}  fips2Postal     – function to convert a fips code to a postal code.
* @export {function}  postal2Fips     – function to convert a postal code to a fips code.
*/

const fipsByPostal = {
  'AK': '02',
  'AL': '01',
  'AR': '05',
  'AS': '60',
  'AZ': '04',
  'CA': '06',
  'CO': '08',
  'CT': '09',
  'DC': '11',
  'DE': '10',
  'FL': '12',
  'GA': '13',
  'GU': '66',
  'HI': '15',
  'IA': '19',
  'ID': '16',
  'IL': '17',
  'IN': '18',
  'KS': '20',
  'KY': '21',
  'LA': '22',
  'MA': '25',
  'MD': '24',
  'ME': '23',
  'MI': '26',
  'MN': '27',
  'MO': '29',
  'MS': '28',
  'MT': '30',
  'NC': '37',
  'ND': '38',
  'NE': '31',
  'NH': '33',
  'NJ': '34',
  'NM': '35',
  'NV': '32',
  'NY': '36',
  'OH': '39',
  'OK': '40',
  'OR': '41',
  'PA': '42',
  'PR': '72',
  'RI': '44',
  'SC': '45',
  'SD': '46',
  'TN': '47',
  'TX': '48',
  'UT': '49',
  'VA': '51',
  'VI': '78',
  'VT': '50',
  'WA': '53',
  'WI': '55',
  'WV': '54',
  'WY': '56',
};

const postalFipsList = Object.keys(fipsByPostal).map(postal => ({postal, FIPS: fipsByPostal[postal]}));

const convertListToDict = (list, Keykey, valueKey) => {
  let output = {};
  list.forEach(item => { output[item[Keykey]] = item[valueKey]; });
  return output;
};

const postalByFips = convertListToDict(postalFipsList, 'FIPS', 'postal');

const fips2Postal = (fips) => postalByFips[fips];

const postal2Fips = (postal) => fipsByPostal[postal];

module.exports = {
  postalFipsList,
  fipsByPostal,
  postalByFips,
  fips2Postal,
  postal2Fips,
};