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ExpressJS

Express is a minimal and flexible Node.js framework that gives us a tools to build web applications and APIs with ease.

Middlewares​

Middleware functions run before sending a response.

Built-in Middlewares​

app.use(express.static("public"));
app.use(express.json()); // Parses JSON body
app.use(express.urlencoded({ extended: true })); // Parses URL-encoded bodies

Error Handling Middlewares​

app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).json({ error: "Something went wrong!" });
});

Third-party Middlewares​

npm install morgan cors
app.use(cors());            // Enables CORS
app.use(morgan('dev'));     // Logs requests

Request/Response Lifecycle​