Lesson 20 / 30
process.env
Configure apps per environment with process.env, safe defaults and inline environment variables.
Reading variables
process.env exposes environment variables as strings — always provide a fallback.
const port = process.env.PORT || 3000;
const env = process.env.NODE_ENV || "development";
console.log(`Starting in ${env} mode on port ${port}`);Setting them
Set variables inline before the command, or export them for the session.
PORT=4000 NODE_ENV=production node server.js
# or
export NODE_ENV=production
node server.js