Express.js Complete Guide 🚀

1. Introduction

Express.js is a minimal Node.js framework used to build APIs and web servers easily.

const express = require("express");
const app = express();

2. Basic Server

app.get("/", (req,res)=>{
  res.send("Hello Express");
});

app.listen(3000);

3. Routing

app.get("/about", (req,res)=>{
  res.send("About Page");
});

4. Middleware

app.use((req,res,next)=>{
  console.log("Request received");
  next();
});

5. JSON Handling

app.use(express.json());

app.post("/data", (req,res)=>{
  console.log(req.body);
  res.send("Data received");
});

6. Router

const router = express.Router();

router.get("/", (req,res)=>{
  res.send("User route");
});

app.use("/user", router);

7. Params

app.get("/user/:id", (req,res)=>{
  res.send(req.params.id);
});

8. Query

app.get("/search", (req,res)=>{
  res.send(req.query.name);
});

9. Static Files

app.use(express.static("public"));

10. Error Handling

app.use((err,req,res,next)=>{
  res.status(500).send("Error");
});