Route parameters in React - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a route with a parameter named 'id'.

React

import { BrowserRouter, Routes, Route } from 'react-router-dom';

function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route path="/user/[1]" element={<User />} />
      </Routes>
    </BrowserRouter>
  );
}

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

A*id

B/id

C{id}

D:id

Attempts:

3 left

💡 Hint

Common Mistakes

Using slashes or braces instead of a colon for parameters.

Forgetting the colon before the parameter name.

In React Router, route parameters are defined with a colon before the parameter name, like :id.

2fill in blank

medium

Complete the code to access the 'id' parameter inside the User component using React Router hooks.

React

import { useParams } from 'react-router-dom';

function User() {
  const params = [1]();
  return <h1>User ID: {params.id}</h1>;
}

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

AuseRouteMatch

BuseLocation

CuseParams

DuseNavigate

Attempts:

3 left

💡 Hint

Common Mistakes

Using hooks that do not provide route parameters like useLocation or useNavigate.

Trying to access params without using the hook.

The useParams hook returns an object of route parameters. Here, params.id accesses the 'id' parameter.

3fill in blank

hard

Fix the error in the code to correctly extract the 'postId' parameter from the URL.

React

function Post() {
  const { [1] } = useParams();
  return <div>Post ID: {postId}</div>;
}

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

ApostId

Bid

Cpostid

Dpost_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect casing like 'postid' or 'post_id'.

Using a different parameter name than defined in the route.

The parameter name must exactly match the route parameter name, which is 'postId' here.

4fill in blank

hard

Fill both blanks to create a route for 'productId' and access it inside the Product component.

React

import { useParams } from 'react-router-dom';

function Product() {
  const { [1] } = useParams();
  return <p>Product: {productId}</p>;
}

function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route path="/product/[2]" element={<Product />} />
      </Routes>
    </BrowserRouter>
  );
}

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

AproductId

B:id

C:productId

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatch between parameter names in route and component.

Forgetting the colon in the route path parameter.

The route parameter is named 'productId', so the path uses ':productId' and the component extracts 'productId' from useParams().

5fill in blank

hard

Fill all three blanks to create a route with two parameters and access them inside the Order component.

React

import { useParams } from 'react-router-dom';

function Order() {
  const { [1], [2] } = useParams();
  return <div>Order {orderId} for user {userId}</div>;
}

function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route path="/order/[3]/:userId" element={<Order />} />
      </Routes>
    </BrowserRouter>
  );
}

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

AorderId

BuserId

C:orderId

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent parameter names between route and component.

Forgetting the colon before parameters in the route path.

The route has two parameters: 'orderId' and 'userId'. The path uses ':orderId' and ':userId'. The component extracts both from useParams().

Practice

1. What does the useParams() hook in React Router do?

easy

A. It sets new route paths dynamically.

B. It retrieves the dynamic parameters from the current URL.

C. It navigates to a different route programmatically.

D. It renders a list of all available routes.

Solution

1. Step 1: Understand the purpose of useParams()

   This hook is designed to extract parameters defined in the route path from the URL.

2. Step 2: Compare with other options

   Options A, C, and D describe different React Router features, not useParams().

3. Final Answer:

   It retrieves the dynamic parameters from the current URL. -> Option B

4. Quick Check:

   useParams() = get URL parameters [OK]

Hint: Remember: useParams() reads URL values, not changes routes. [OK]

Common Mistakes:

• Confusing useParams() with navigation functions like useNavigate()
• Thinking useParams() sets or changes routes
• Assuming useParams() returns all routes instead of parameters

2. Which of the following is the correct way to define a route with a parameter named postId in React Router?

easy

A. <Route path="/post/:postId" element={<Post />} />

B. <Route path="/post/*postId" element={<Post />} />

C. <Route path="/post/postId" element={<Post />} />

D. <Route path="/post/{postId}" element={<Post />} />

Solution

1. Step 1: Identify parameter syntax in route paths

   React Router uses a colon : before the parameter name to define dynamic segments.

2. Step 2: Check each option

   <Route path="/post/:postId" element={<Post />} /> correctly uses /:postId. Options A, B, and D use incorrect syntax.

3. Final Answer:

   <Route path="/post/:postId" element={<Post />} /> -> Option A

4. Quick Check:

   Parameter syntax = colon before name [OK]

Hint: Use colon before parameter name in route path. [OK]

Common Mistakes:

• Omitting the colon before parameter name
• Using curly braces or asterisk instead of colon
• Confusing parameter syntax with query strings

3. Given the route <Route path="/profile/:username" element={<Profile />} /> and the URL /profile/jane_doe, what will useParams() return inside the Profile component?

medium

A. {"username": ":jane_doe"}

B. {"profile": "jane_doe"}

C. {"username": "jane_doe"}

D. {} (empty object)

Solution

1. Step 1: Match URL segment to route parameter

   The route defines :username as a parameter. The URL /profile/jane_doe assigns "jane_doe" to this parameter.

2. Step 2: Understand useParams() output

   useParams() returns an object with keys as parameter names and values as the matched URL parts.

3. Final Answer:

   {"username": "jane_doe"} -> Option C

4. Quick Check:

   useParams() returns {paramName: value} [OK]

Hint: useParams() keys match route parameters exactly. [OK]

Common Mistakes:

• Including colon in parameter value
• Using wrong parameter name as key
• Expecting empty object when parameter exists

4. Consider this code snippet inside a React Router app:

const params = useParams();
console.log(params.id);

But the route is defined as <Route path="/product/:productId" element={<Product />} />. What is the problem?

medium

A. The parameter name used in useParams() does not match the route parameter name.

B. useParams() cannot be used inside functional components.

C. The route path should not have a colon before the parameter name.

D. The element prop must be a string, not a component.

Solution

1. Step 1: Compare parameter names in route and code

   The route defines parameter as productId, but code accesses params.id.

2. Step 2: Understand useParams() object keys

   useParams() keys exactly match route parameter names, so params.id is undefined here.

3. Final Answer:

   The parameter name used in useParams() does not match the route parameter name. -> Option A

4. Quick Check:

   Param names must match exactly [OK]

Hint: Check parameter names match exactly in route and useParams(). [OK]

Common Mistakes:

• Assuming useParams() keys are generic like 'id'
• Thinking useParams() works outside components
• Misunderstanding route parameter syntax

5. You want to create a route that shows a user's post by user ID and post ID, like /user/42/post/7. Which route path and useParams() usage correctly extract both parameters inside the component?

hard

A. <Route path="/user/:userId/post/:postId" element={<UserPost />} />Inside component: const [userId, postId] = useParams();

B. <Route path="/user/:userId/post/:postId" element={<UserPost />} />Inside component: const params = useParams(); const user = params.user; const post = params.post;

C. <Route path="/user/:userId/post/:postId" element={<UserPost />} />Inside component: const { id1, id2 } = useParams();

D. <Route path="/user/:userId/post/:postId" element={<UserPost />} />Inside component: const { userId, postId } = useParams();

Solution

1. Step 1: Define route with multiple parameters

   The route path correctly uses :userId and :postId to capture both values.

2. Step 2: Correctly extract parameters inside component

   useParams() returns an object, so destructuring with matching keys { userId, postId } is correct. Options A, B, and C misuse keys or destructuring.

3. Final Answer:

   <Route path="/user/:userId/post/:postId" element={<UserPost />} /> with const { userId, postId } = useParams(); -> Option D

4. Quick Check:

   Multiple params = multiple keys in useParams() object [OK]

Hint: Destructure useParams() with exact route parameter names. [OK]

Common Mistakes:

• Using wrong keys when destructuring useParams()
• Trying to destructure useParams() as an array
• Accessing non-existent keys from useParams()