Resource-based route organization in Express - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Express route handler?

Consider this Express route setup for a resource /books. What will be the response when a GET request is made to /books/42?

Express

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

app.get('/books/:id', (req, res) => {
  res.send(`Book ID is ${req.params.id}`);
});

// Assume app.listen is called elsewhere

A 404 Not Found

B Book ID is 42

C Error: Cannot read property 'id' of undefined

D Book ID is :id

💡 Hint

Look at how req.params works in Express routes with parameters.

The route /books/:id captures the part after /books/ as req.params.id. So when you visit /books/42, req.params.id is 42. The handler sends back Book ID is 42.

📝 Syntax

intermediate

Which option correctly defines a resource route for creating a new user?

You want to add a POST route to /users to create a new user. Which code snippet correctly sets this up in Express?

A app.post('/users', (req, res) => { res.send('User created'); });

B app.get('/users/create', (req, res) => { res.send('User created'); });

C app.put('/users', (req, res) => { res.send('User created'); });

D app.post('/users/:id', (req, res) => { res.send('User created'); });

💡 Hint

Think about which HTTP method is used to create resources and the typical URL pattern.

POST to /users is the standard way to create a new user resource. GET is for reading, PUT is for updating, and POST with an ID in the URL is unusual for creation.

🔧 Debug

advanced

Why does this resource route handler not respond as expected?

Given this Express route, a GET request to /products/123 hangs and never sends a response. What is the cause?

Express

app.get('/products/:id', (req, res) => {
  const productId = req.params.id;
  // Missing res.send or res.end
});

A The handler does not send a response, so the request hangs.

B The route path is incorrect; it should be '/product/:id'.

C req.params.id is undefined causing an error.

D Express requires next() to be called to complete the request.

💡 Hint

Check if the handler sends a response back to the client.

The route handler reads the parameter but never calls res.send() or similar. Without sending a response, the client waits indefinitely.

🧠 Conceptual

advanced

What is the main benefit of organizing routes by resource in Express?

Why do developers prefer grouping routes by resource (like /users, /orders) in Express applications?

A It prevents unauthorized access by restricting routes to resource folders.

B It improves server performance by caching resource routes automatically.

C It allows Express to automatically generate HTML views for each resource.

D It makes the code easier to maintain and understand by keeping related routes together.

💡 Hint

Think about how organizing code affects readability and maintenance.

Grouping routes by resource helps developers find and update related routes easily. It does not affect performance, view generation, or security directly.

❓ state_output

expert

What is the final value of the variable routesCount after this Express router setup?

Given this code that organizes routes for a resource, what is the value of routesCount after all routes are added?

Express

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

let routesCount = 0;

router.get('/', (req, res) => res.send('List'));
routesCount++;

router.post('/', (req, res) => res.send('Create'));
routesCount++;

router.get('/:id', (req, res) => res.send('Read'));
routesCount++;

router.put('/:id', (req, res) => res.send('Update'));
routesCount++;

router.delete('/:id', (req, res) => res.send('Delete'));
routesCount++;

module.exports = router;

A 6

B 4

C 5

D 0

💡 Hint

Count how many routes are defined and increment routesCount.

There are exactly 5 routes defined: GET /, POST /, GET /:id, PUT /:id, DELETE /:id. Each increments routesCount by 1, so final value is 5.