Javascript map for US zipcode -> lat,long lookups. Nothing fancy, just a big javascript map and a utility function. It's just under 2MB -- so it's big for javascript, but not unmanageable.
Keep in mind that this will add about 10 minutes to your webpack build time if you include this in your project.
Data from https://gist.github.com/erichurst/7882666
import ZipToGeo from '../utility/ziptogeo';
let lat, long;
({lat, long} = ZipToGeo("30019"));
// lat should be 33.97561
// long should be -83.883747