12.6 Common backend API for MEAN and MERN (Node + Express + MongoDB)

sudo mkdir -p /opt/notes-api && sudo chown $USER:$USER /opt/notes-api
cd /opt/notes-api
npm init -y
npm install express mongoose dotenv

cat > .env <<'EOF'
PORT=5000
MONGO_URL=mongodb://127.0.0.1:27017/notesdb
EOF

cat > server.js <<'EOF'
require("dotenv").config();
const express = require("express");
const mongoose = require("mongoose");

const app = express();
app.use(express.json());

mongoose.connect(process.env.MONGO_URL)
  .then(() => console.log("MongoDB connected"))
  .catch((err) => { console.error("MongoDB error:", err.message); process.exit(1); });

const Note = mongoose.model("Note",
  new mongoose.Schema({ text: { type: String, required: true } }, { timestamps: true }));

app.get("/api/health", (req, res) => res.json({ status: "ok" }));

app.get("/api/notes", async (req, res) => {
  res.json(await Note.find().sort({ createdAt: -1 }));
});

app.post("/api/notes", async (req, res) => {
  try {
    res.status(201).json(await Note.create({ text: req.body.text }));
  } catch (err) {
    res.status(400).json({ error: err.message });
  }
});

app.delete("/api/notes/:id", async (req, res) => {
  await Note.findByIdAndDelete(req.params.id);
  res.status(204).end();
});

const port = process.env.PORT || 5000;
app.listen(port, "127.0.0.1", () => console.log(`API on 127.0.0.1:${port}`));
EOF

pm2 start server.js --name notes-api
pm2 save
curl -s -X POST http://127.0.0.1:5000/api/notes -H "Content-Type: application/json" -d '{"text":"First note"}'
curl -s http://127.0.0.1:5000/api/notes