How to include given mode in index.js - node.js

Question

I have this given module in config.js. I want to include this is my index.js. I tried multiple ways but config variable is always undefined.
I tried like this.
const config = require('./config') //undefined
const config = require('./config')("dev") //error
const config = require('./config')["dev"] // error
const config = require('./config').get("dev")
Here is how i run it
// my command.
npm run start:dev
"scripts": {
"start:prod": "set NODE_ENV=prod pm2 start index.js --watch",
"start:dev": "set NODE_ENV=dev && node index.js"
},
Here is module
let env = process.env.NODE_ENV;
require('dotenv').config();
const dev = {
app: {
port: parseInt(process.env.DEV_APP_PORT) || 3000
},
db: {
host: process.env.DEV_DB_HOST || 'localhost',
port: parseInt(process.env.DEV_DB_PORT) || 27017,
name: process.env.DEV_DB_NAME || 'myDB',
},
imagePath: "./profileImages/",
LogFillePath: "logs/combined.log",
ErrorFilePaht: "logs/error.log",
JwtSecret: process.env.JWT_SECRET
};
const prod = {
app: {
port: parseInt(process.env.PROD_APP_PORT) || 9000
},
db: {
host: process.env.PROD_DB_HOST || 'localhost',
port: parseInt(process.env.PROD_DB_PORT) || 27017,
name: process.env.PROD_DB_NAME || 'myDB'
},
imagePath: "./profileImages/",
LogFillePath: "logs/combined.log",
ErrorFilePaht: "logs/error.log",
JwtSecret: process.env.JWT_SECRET
};
const config = {
dev,
prod
};
module.exports = config[env];
I have this given module in config.js. I want to include this is my index.js. I tried multiple ways but config variable is always undefined.
I tried like this.

Answer 1

Try something like this for your config.js:
require("dotenv").config();
const dev = {
// ...
};
const prod = {
// ...
};
const configs = {
dev,
prod,
};
const config = configs[process.env.NODE_ENV];
if (!config) throw new Error("No valid configuration found, ensure your NODE_ENV is properly set");
module.exports = config;
Then you can simply
const config = require('./config');