Express ~ Environment Configuration - rohit120582sharma/Documentation GitHub Wiki

An environment variable is basically a variable that is part of the environment in which a process runs and it's value is set outside the application. So typically in hosting environment for node applications, we have environment variable called PORT.

Use environment variables for anything you need to change or configure in your code that will change based on the environment.

common scenarios:

• Which HTTP port to listen on
• What path and folder your files are located in, that you want to serve
• Pointing to a development, staging, test, or production database

Set an environment variable:

// OS X / Linux:
export PORT=5000

// Windows:
set PORT=5000

const express = require(‘express’);
const app = express();

// Check the environment
if(process.env.NODE_ENV === 'development'){
	// Connect to development database
}else if(process.env.NODE_ENV === 'production'){
	// Connect to production database
}

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
	console.log(`Listening on port ${PORT}...`);
});