Lesson 8 — Env config

Settings with safe defaults

Servers read settings like the port from environment variables — values set outside the code. In Node they live in process.env (for example process.env.PORT). If a setting is missing, use a default with ?? ("if null or undefined, use this instead").

const timeout = env.TIMEOUT ?? 5000;

Note: this playground runs JavaScript in your browser, not in real Node, so Node-only tools (like fs or http) are not available. The exercise is a small plain-JS simulation of the Node idea. Here env is a plain object standing in for process.env.

Why it matters: the same code runs on your laptop and in production, just with different settings.