The frontend (JavaScript + React) is what users see. The backend is the server behind
it: it holds the data, enforces the rules, and answers the frontend's fetch calls. Here
you'll build the actual /api/notes server your Notes app has been talking to — and finally
see how frontend and backend connect.
Module 1 built the Notes frontend in JavaScript. Module 2 rebuilt it in React. Both called fetch("/api/notes") against a mock server. This module builds the real server — and the visualizer in section 5 shows the full round-trip: browser → API → data → back to the screen.
Frontend vs backend, and why an app needs a server at all.
JavaScript on a server, and the tiny framework that makes web servers easy.
Matching a method + URL to a handler — GET, POST, DELETE.
Build the real /api/notes endpoints with an in-memory store.
Animated: browser → fetch → Express → data → JSON → React render. The whole round-trip.
The one error everyone hits connecting frontend to backend — and how deploy works.
The complete picture: React + Express + database, one Notes app end to end.