Day 41 of Learning MERN stack

Hello Dev Community! 👋 It is officially Day 41 of my continuous streak toward full-stack MERN engineering! Yesterday, I migrated my codebase from native Node boilerplate to Express.js. Today, I dived straight into the absolute core mechanism that makes Express so incredibly powerful in Prashant Sir's (Complete Coding) masterclass : Middlewares . Before today, I thought requests hit an endpoint and immediately returned a response. Today, I learned how to intercept, inspect, and modify that request before it ever reaches the final route handler! 🧠 Key Learnings From Node.js Lecture 9 (Middlewares) A middleware is essentially a function that executes during the Request-Response cycle, having full access to the req , res , and the next middleware function in line. Here is the technical breakdown: 1. The Anatomy of Middleware Unlike a standard route handler that takes (req, res) , a middleware takes a third powerful argument: next . If you don't invoke next() , your request will hang forever and the browser will eventually timeout! 2. Built-in vs. Custom Middleware Custom Middleware: Wrote my own custom functions using app.use((req, res, next) => { ... }) to act as a security guard or global logger. Built-in Middleware: Explored how Express natively handles data types using structures like express.json() and express.urlencoded() , which automatically parse inbound request bodies so we don't have to manually handle streams anymore! javascript const express = require("express"); const app = express(); // Custom Global Logging Middleware app.use((req, res, next) => { console.log(`[${new Date().toISOString()}] ${req.method} request to ${req.url}`); next(); // Pass control to the next handler in line! }); app.get("/dashboard", (req, res) => { res.send("Welcome to the secure dashboard layer!"); }); app.listen(8000);