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TypeScript Academy · Lesson

Environment Variables and Config Typing

Type process.env with a validated config module.

Welcome

Typing process.env prevents runtime errors from missing or mistyped environment variables.

The Problem

process.env values are always string | undefined. Accessing them without checking causes bugs.
const port = process.env.PORT; // string | undefined
// server.listen(port); // could be undefined!

All lessons in this course

  1. Setting Up TypeScript with Node.js
  2. Typing Express Request and Response
  3. Typed Middleware and Error Handlers
  4. Environment Variables and Config Typing
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