env-default

Grabs the first defined variable from either environment variables, npm package config or as a supplied value

$ npm i -S env-default

// index.js

var def = require( 'env-default' )

console.log( def( 'HOST', '0.0.0.0'), def( 'PORT', 3000 ) )

$ PORT=5001 node index.js
$ 0.0.0.0 5001