Creating Routes and Handling Requests with Express.js (Complete Beginner Guide)

Introduction

When building backend applications, handling requests and defining routes is one of the most important tasks.

Using Express.js, this becomes extremely simple and clean compared to raw Node.js.

In this guide, you’ll learn:

• What Express.js is

• Why it simplifies development

• How to create a server

• Handling GET & POST requests

• Sending responses

• Understanding routing clearly

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What is Express.js?

Express.js is a minimal and flexible web framework for Node.js

It helps you:

• Create servers easily

• Define routes cleanly

• Handle requests & responses

• Build APIs faster

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Why Express is Better than Raw Node.js

Let’s compare

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Raw Node.js Server

import http from "http";

const server = http.createServer((req, res) => {
  if (req.url === "/") {
    res.write("Home Page");
    res.end();
  }
});

server.listen(3000);

Problems:

• Manual routing

• Hard to scale

• Messy code

---

Express Server

import express from "express";

const app = express();

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

app.listen(3000);

Benefits:

• Clean syntax

• Easy routing

• Scalable

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Creating Your First Express Server

Step 1: Install Express

npm install express

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Step 2: Create Server

import express from "express";

const app = express();

app.listen(3000, () => {
  console.log("Server running on http://localhost:3000");
});

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Request → Route → Response Flow

Flow:

Client Request → Route Handler → Response

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Understanding Routing in Express

Routing means:

Defining how your server responds to different URLs

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Basic Route Syntax

app.METHOD(PATH, HANDLER)

Example:

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

---

Handling GET Requests

GET is used to fetch data

app.get("/users", (req, res) => {
  res.send("List of users");
});

Open:

http://localhost:3000/users

---

Handling POST Requests

POST is used to send data

---

Step 1: Enable JSON Middleware

app.use(express.json());

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Step 2: Create POST Route

app.post("/users", (req, res) => {
  const user = req.body;
  res.send(`User created: ${user.name}`);
});

---

Example Request Body

{
  "name": "Ankit"
}

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Sending Responses in Express

Express provides multiple response methods:

---

Send Text

res.send("Hello World");

---

Send JSON

res.json({ name: "Ankit", age: 22 });

---

Send Status Code

res.status(200).send("Success");

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Multiple Routes Example

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

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

app.post("/login", (req, res) => {
  res.send("Login Successful");
});

---

Understanding req and res

req (Request):

• Contains incoming data

• URL, body, headers

res (Response):

• Used to send data back

• Controls output

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Real-World Example (Mini API)

const users = [];

app.post("/users", (req, res) => {
  users.push(req.body);
  res.json(users);
});

app.get("/users", (req, res) => {
  res.json(users);
});

---

Common Beginner Mistakes

• Forgetting express.json()

• req.body will be undefined

• Wrong route method

• Using GET instead of POST

• Not sending response

• Request hangs

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Best Practices

• Keep routes simple

• Use meaningful paths

• Separate routes into files (for large apps)

• Always send a response

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Easy Analogy

Think of Express like a restaurant

• Customer = Request

• Menu path = Route

• Chef = Handler

• Food = Response

Customer orders → Chef prepares → Food served

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Conclusion

Now you understand:

✔ What Express.js is
✔ Why it simplifies Node.js
✔ Creating server
✔ Handling GET & POST requests
✔ Sending responses
✔ Routing concept clearly