🛠️ Node.js Backend Setup

Time to build your AI backend! 🚀

We’re using Node.js + Express because it’s simple, reliable, and works with any frontend (React, Vue, mobile apps, browser extensions). Plus, you have full control over your server.

Why not Next.js? Serverless functions can be tricky with file uploads and long-running AI processes. A standalone backend keeps things predictable.

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📁 Step 1: Create Your Project

Let’s set up your workspace:

mkdir openai-backend
cd openai-backend
npm init -y

Create your environment file:

touch .env
echo "node_modules/" > .gitignore
echo ".env" >> .gitignore

What just happened? You created a Node project and protected your secrets from being committed to Git.

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📦 Step 2: Install Dependencies

Core packages:

npm install express cors dotenv openai

Development tools:

npm install -D nodemon

What each package does:

• express - Your web server (handles HTTP requests)
• cors - Lets your frontend talk to your backend
• dotenv - Loads your API keys securely
• openai - Official OpenAI JavaScript client
• nodemon - Auto-restarts server when you make changes

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⚙️ Step 3: Configure Modern JavaScript

Update your package.json to enable modern JavaScript:

{
  "name": "openai-backend",
  "version": "1.0.0",
  "type": "module",
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon index.js"
  },
  "dependencies": {
    // your packages will be here
  }
}

Key change: "type": "module" lets you use import instead of require(). Much cleaner!

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🔑 Step 4: Add Your API Key

Open .env and add your OpenAI API key:

OPENAI_API_KEY=sk-proj-your-actual-key-here
PORT=8000

Replace sk-proj-your-actual-key-here with your real API key from the previous lesson.

Security reminder: Never commit .env to Git. Your .gitignore already protects you.

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🛠️ Step 5: Create Your Server

Create index.js:

import express from "express";
import { config } from "dotenv";
import cors from "cors";

// Load environment variables
config();

const app = express();
const PORT = process.env.PORT || 8000;

// Middleware
app.use(cors()); // Allow frontend connections
app.use(express.json()); // Parse JSON requests

// Test route
app.get("/", (req, res) => {
  res.json({
    message: "🤖 OpenAI Backend is running!",
    status: "ready"
  });
});

// Start server
app.listen(PORT, () => {
  console.log(`🚀 Server running on http://localhost:${PORT}`);
  console.log(`📚 Ready for OpenAI integration!`);
});

What this code does:

• Creates an Express server on port 8000
• Enables CORS so your frontend can connect
• Parses JSON requests automatically
• Provides a test endpoint to verify everything works

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🧪 Step 6: Test Your Server

Start your server:

npm run dev

You should see:

🚀 Server running on http://localhost:8000
📚 Ready for OpenAI integration!

Test in your browser: Visit http://localhost:8000

Success looks like:

{
  "message": "🤖 OpenAI Backend is running!",
  "status": "ready"
}

Test with curl:

curl http://localhost:8000

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🔧 Troubleshooting Common Issues

“Cannot use import statement”

• ✅ Add "type": "module" to your package.json

“Port 8000 already in use”

• ✅ Change PORT=8001 in your .env file

“command not found: npm”

• ✅ Install Node.js from nodejs.org

Server starts but can’t connect

• ✅ Check your firewall settings
• ✅ Try http://127.0.0.1:8000 instead

“Cannot find module ‘express’”

• ✅ Run npm install again
• ✅ Make sure you’re in the right directory

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📂 Your Project Structure

Your backend should look like this:

openai-backend/
├── index.js          # Your main server file
├── package.json      # Project configuration
├── .env              # API keys (never commit!)
├── .gitignore        # Protects secrets
└── node_modules/     # Dependencies (auto-generated)

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Perfect! Your backend is ready for AI integration. 🎉

What’s next? We’ll connect to OpenAI and create your first AI endpoint. Time to make your server intelligent!

👉 Next: Your First AI Endpoint - Let’s add some AI magic!