parser.js

const params = {
  host: {
    description: 'PostgreSQL host',
    boolean: false
  }
};

// cliParams is a mapping between param keys and a cli param keys
const cliParams = { host: 'host' };
const envParams = { host: 'PGHOST' };

parse(params)
  .cli(cliParams)
  .env(envParams)
  .dotEnv(envParams);