API versioning strategies in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set up a basic Express server.

Node.js

const express = require('[1]');
const app = express();
app.listen(3000, () => console.log('Server running'));

Drag options to blanks, or click blank then click option'

Apath

Bhttp

Cexpress

Dfs

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'http' instead of 'express' to create the server.

The Express library is required to create the server.

2fill in blank

medium

Complete the code to define a versioned API route using URL path versioning.

Node.js

app.use('/api/[1]/users', (req, res) => res.send('User list'));

Drag options to blanks, or click blank then click option'

Av1

Bv2

Cversion1

Dapi

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'api' instead of a version number in the path.

Using 'v1' in the URL path is a common way to version APIs.

3fill in blank

hard

Fix the error in the code to read the API version from a custom header.

Node.js

app.use((req, res, next) => {
  const version = req.headers['[1]'];
  if (version === '1') next();
  else res.status(400).send('Invalid API version');
});

Drag options to blanks, or click blank then click option'

Aapi-version

Bapi_version

Cversion

Dx-api-version

Attempts:

3 left

💡 Hint

Common Mistakes

Using standard header names that don't exist.

Custom headers often use the 'x-' prefix, like 'x-api-version'.

4fill in blank

hard

Fill both blanks to implement query parameter versioning in Express.

Node.js

app.get('/users', (req, res) => {
  const version = req.query.[1];
  if (version === '[2]') res.send('User list v1');
  else res.status(400).send('Unsupported version');
});

Drag options to blanks, or click blank then click option'

Aversion

Bv

Cv1

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'v' as the query parameter name instead of 'version'.

The query parameter 'version' is checked for the value 'v1' to serve version 1 of the API.

5fill in blank

hard

Fill all three blanks to implement header versioning with middleware.

Node.js

app.use((req, res, next) => {
  const version = req.headers['[1]'];
  if (version === '[2]') {
    req.apiVersion = '[3]';
    next();
  } else {
    res.status(400).send('Invalid API version');
  }
});

Drag options to blanks, or click blank then click option'

Ax-api-version

Bv1

C1

Dapi-version

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'api-version' without the 'x-' prefix.

The middleware reads the 'x-api-version' header, checks for 'v1', and sets the internal version to '1'.

Practice

1. Which of the following is the simplest and most common method to version a Node.js API?

easy

A. Using content negotiation with the Accept header

B. Using a custom HTTP header to specify the version

C. Adding a version query parameter, like ?version=1

D. Including the version number in the URL path, like /v1/users

Solution

1. Step 1: Understand common API versioning methods

   API versioning can be done via URL path, headers, query params, or content negotiation.

2. Step 2: Identify the simplest and most common method

   Including the version in the URL path is easiest to implement and understand.

3. Final Answer:

   Including the version number in the URL path, like /v1/users -> Option D

4. Quick Check:

   URL path versioning = simplest method [OK]

Hint: URL path versioning is easiest to spot and use [OK]

Common Mistakes:

• Thinking headers are simpler for beginners
• Confusing query params with URL path
• Assuming content negotiation is the default

2. Which syntax correctly defines a route in Express.js for version 2 of an API using URL path versioning?

easy

A. app.get('/api/v2/users', (req, res) => { res.send('v2 users'); });

B. app.get('/api/users?v=2', (req, res) => { res.send('v2 users'); });

C. app.get('/api/users', (req, res) => { if(req.headers['version'] === '2') res.send('v2 users'); });

D. app.get('/api/users', (req, res) => { res.send('v2 users'); });

Solution

1. Step 1: Recognize URL path versioning syntax in Express.js

   Version 2 in URL path means the route includes /v2/ in the path.

2. Step 2: Match the correct route definition

   app.get('/api/v2/users', (req, res) => { res.send('v2 users'); }); uses /api/v2/users which matches version 2 in the URL path.

3. Final Answer:

   app.get('/api/v2/users', (req, res) => { res.send('v2 users'); }); -> Option A

4. Quick Check:

   URL path versioning route = app.get('/api/v2/users', (req, res) => { res.send('v2 users'); }); [OK]

Hint: Version in URL path means it appears in the route string [OK]

Common Mistakes:

• Using query params instead of URL path
• Checking headers inside route without version in path
• Ignoring version in route path

3. Given this Express.js code snippet, what will be the response when a client requests /api/users with header Accept-Version: 2?

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

app.get('/api/users', (req, res) => {
  if (req.headers['accept-version'] === '2') {
    res.send('Users v2');
  } else {
    res.send('Users v1');
  }
});

medium

A. "Users v1"

B. 404 Not Found

C. "Users v2"

D. Error: Missing version

Solution

1. Step 1: Check the header condition in the route handler

   The code checks if req.headers['accept-version'] equals '2'.

2. Step 2: Determine response based on header value

   If header is '2', it sends 'Users v2'; otherwise, 'Users v1'. The request has header 'Accept-Version: 2'.

3. Final Answer:

   "Users v2" -> Option C

4. Quick Check:

   Header 'Accept-Version: 2' triggers v2 response [OK]

Hint: Match header value exactly to get correct version response [OK]

Common Mistakes:

• Ignoring case sensitivity of header keys
• Assuming URL path versioning instead of header
• Expecting 404 when route exists

4. Identify the bug in this Express.js versioning code using query parameters:

app.get('/api/users', (req, res) => {
  if (req.query.version = '1') {
    res.send('Users v1');
  } else {
    res.send('Users v2');
  }
});

medium

A. Missing route for version 2 explicitly

B. Using assignment (=) instead of comparison (== or ===) in the if condition

C. Incorrect query parameter name; should be 'ver' not 'version'

D. res.send should be res.json for API responses

Solution

1. Step 1: Examine the if condition syntax

   The condition uses = which assigns '1' to req.query.version instead of comparing.

2. Step 2: Understand the effect of assignment in condition

   Assignment returns '1' (truthy), so the if block always runs, ignoring else.

3. Final Answer:

   Using assignment (=) instead of comparison (== or ===) in the if condition -> Option B

4. Quick Check:

   Use '==' or '===' for comparison, not '=' [OK]

Hint: Use triple equals (===) for comparisons, not single equals (=) [OK]

Common Mistakes:

• Confusing assignment with equality check
• Assuming missing else block causes bug
• Thinking res.send vs res.json causes error here

5. You want to support two API versions in your Node.js app: v1 uses URL path versioning, and v2 uses a custom header X-API-Version. How should you design your Express routes to handle both cleanly?

hard

A. Define separate routes: /api/v1/... for v1, and /api/... with header check for v2

B. Use only URL path versioning for both versions to avoid confusion

C. Use query parameters for v1 and headers for v2 in the same route

D. Combine both version indicators in the URL path like /api/v1/v2/...

Solution

1. Step 1: Separate versioning methods logically

   Use URL path for v1 routes explicitly, e.g., /api/v1/....

2. Step 2: Use header check for v2 on routes without version in path

   Define routes like /api/... and check X-API-Version header to serve v2.

3. Final Answer:

   Define separate routes: /api/v1/... for v1, and /api/... with header check for v2 -> Option A

4. Quick Check:

   Separate routes for path and header versioning [OK]

Hint: Separate routes for path versioning; use header check for others [OK]

Common Mistakes:

• Mixing both versions in one URL path
• Using query params inconsistently
• Ignoring header version check in routes