var PostalCodes = require('postal-codes');

var postalCodes = new PostalCodes();

// Get supported countries
postalCodes.supportedCountries().then(function(value) {
  value.countryCodes; //->  Array of ISO 3166-1 alpha-2 country codes
});

// Get some postal code
postalCodes.area({
  countryCode: "US",
  postalCode: "90210"
}).then(function(value) {
  value.countryCode; //-> "US"
  value.id;          //-> "90210"
  value.polygons;    //-> Array of polygons that represent this postal code
});