Routing in Express

Express.js makes it easy to define routes for various HTTP methods and handle dynamic and query parameters efficiently.

Defining Routes for HTTP Methods

Express supports multiple HTTP methods like GET, POST, PUT, and DELETE. Here’s how you can define routes for these methods:

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

// Handling GET request
app.get("/home", (req, res) => {
  res.send("Welcome to the homepage!");
});

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

// Handling PUT request
app.put("/user/:id", (req, res) => {
  res.send(`User ${req.params.id} updated`);
});

// Handling DELETE request
app.delete("/user/:id", (req, res) => {
  res.send(`User ${req.params.id} deleted`);
});

Creating Dynamic Routes with URL Parameters

Dynamic routes allow you to capture values from the URL. This is done using URL parameters, which are defined with a colon (:) prefix.

app.get("/users/:id", (req, res) => {
  const userId = req.params.id;
  res.send(`User ID: ${userId}`);
});

• The :id part of the route captures the value from the URL.
• The captured value can be accessed using req.params.id.

Handling Query Parameters

Query parameters are key-value pairs appended to the URL after a ?. Express allows you to access these parameters using req.query.

app.get("/search", (req, res) => {
  const searchTerm = req.query.term;
  res.send(`Search term: ${searchTerm}`);
});

• The query parameter term is accessed using req.query.term.
• This allows handling of requests like /search?term=express.

Route Grouping using express.Router()

For modularizing routes, use express.Router() to group routes logically.

const express = require("express");
const router = express.Router();

// Define routes for /users
router.get("/", (req, res) => {
  res.send("List of users");
});

router.post("/", (req, res) => {
  res.send("Create a new user");
});

// Use the router in the app
app.use("/users", router);

• GET /users serves the list of users.
• POST /users creates a new user.