I just noticed zip code isn't parsed out from the City dat. It should be there for requests. I don't know if it's under Postal Code or Zip Code. But should be there for located cities.
geodata.zip = locBuffer.readInt32BE((locId * locRecordSize) + 16); on lib/geoip.js:110 for ipv4. It looks like ipv6 also includes zip, I'll open a PR for that.
I just noticed zip code isn't parsed out from the City dat. It should be there for requests. I don't know if it's under Postal Code or Zip Code. But should be there for located cities.