env

Environment variables are a must-have in Node.js apps to keep sensitive info (API keys, DB credentials) and environment-specific settings out of your codebase. Let’s go step by step.

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📂 1. Install dotenv

npm install dotenv

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📖 2. Create a .env file

This lives in your project root (and should be gitignored):

PORT=4000
MONGO_URI=mongodb://localhost:27017/mydb
JWT_SECRET=supersecretkey
NODE_ENV=development

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⚡ 3. Load .env in Node.js

In your entry point (server.js or app.js):

require("dotenv").config();
 
console.log("PORT is:", process.env.PORT);
console.log("Environment:", process.env.NODE_ENV);

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🛠️ 4. Using Variables in Your App

Example with Express and MongoDB:

const express = require("express");
const mongoose = require("mongoose");
require("dotenv").config();
 
const app = express();
 
// Connect to MongoDB
mongoose.connect(process.env.MONGO_URI)
  .then(() => console.log("DB connected"))
  .catch(err => console.error("DB error:", err));
 
app.listen(process.env.PORT, () => {
  console.log(`Server running on port ${process.env.PORT}`);
});

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🔐 5. Security & Best Practices

• Never commit .env files → add .env to .gitignore.

• Use .env.example to show required vars without secrets:

  PORT=
  MONGO_URI=
  JWT_SECRET=
  NODE_ENV=
  

• Keep different .env files per environment:

  • .env.development

  • .env.production

👉 Then load the right one based on NODE_ENV.

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✅ In Short

• Use dotenv to load .env files into process.env.

• Store secrets and environment-specific configs there.

• Never commit real .env files to git — use .env.example.

• Access vars via process.env.KEY.

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