DELETE route handling in Express - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the response when deleting an existing item?

Consider this Express DELETE route that removes an item by ID from an array. What will the server respond with if the item exists?

Express

const express = require('express');
const app = express();
app.use(express.json());

let items = [{id: 1, name: 'apple'}, {id: 2, name: 'banana'}];

app.delete('/items/:id', (req, res) => {
  const id = Number(req.params.id);
  const index = items.findIndex(item => item.id === id);
  if (index === -1) {
    return res.status(404).send('Item not found');
  }
  items.splice(index, 1);
  res.status(200).send('Deleted');
});

A Status 200 with body 'Deleted'

B Status 404 with body 'Item not found'

C Status 500 with empty body

D Status 200 with JSON of deleted item

💡 Hint

Check what happens when the item is found and removed.

If the item exists, the route removes it and sends status 200 with 'Deleted'. If not found, it sends 404.

📝 Syntax

intermediate

Which DELETE route syntax is correct?

Which of the following Express DELETE route definitions is syntactically correct?

A app.delete('/items/:id', function(req, res) { res.send('Deleted') }

B app.delete('/items/:id', (req, res) => { res.send('Deleted'); })

C app.delete('/items/:id', (req, res) => res.send('Deleted')

D app.delete('/items/:id', (req, res) => { res.send('Deleted') )

💡 Hint

Look for balanced parentheses and braces.

Option B has correct arrow function syntax with balanced braces and parentheses.

🔧 Debug

advanced

Why does this DELETE route cause a runtime error?

Given this DELETE route, why does the server crash when a request is made?

Express

app.delete('/users/:id', (req, res) => {
  const id = Number(req.params.id);
  const user = users.find(u => u.id === id);
  users = users.filter(u => u.id !== id);
  res.send(`Deleted user ${user.name}`);
});

A Because res.send is missing a status code

B Because users array is not declared

C Because id is a string but user ids are numbers, find returns undefined causing user.name to fail

D Because filter does not remove items from the array

💡 Hint

Check the type of id and how find works.

req.params.id is a string, but user ids are numbers, so find returns undefined. Accessing user.name causes a runtime error.

❓ state_output

advanced

What is the state of the items array after DELETE request?

Given this initial array and DELETE route, what is the content of items after a DELETE request to /items/2?

Express

let items = [{id: 1, name: 'apple'}, {id: 2, name: 'banana'}, {id: 3, name: 'cherry'}];

app.delete('/items/:id', (req, res) => {
  const id = Number(req.params.id);
  items = items.filter(item => item.id !== id);
  res.status(200).send('Deleted');
});

A []

B [{id: 1, name: 'apple'}, {id: 2, name: 'banana'}, {id: 3, name: 'cherry'}]

C [{id: 2, name: 'banana'}]

D [{id: 1, name: 'apple'}, {id: 3, name: 'cherry'}]

💡 Hint

Filter removes items with matching id.

The item with id 2 is removed, so only items with id 1 and 3 remain.

🧠 Conceptual

expert

What is the best practice for DELETE route response content?

When designing an Express DELETE route, which response practice is recommended for RESTful APIs?

A Respond with status 204 No Content and no response body

B Respond with status 200 and the deleted item in JSON

C Respond with status 404 even if deletion succeeds

D Respond with status 200 and a plain text confirmation message

💡 Hint

Think about HTTP status codes and REST conventions.

HTTP 204 No Content is the standard response for successful DELETE with no body.