Defining routes in React - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of defining routes in a React application?

Defining routes lets you decide which component to show when the user visits a specific URL. It helps create different pages or views in a single app.

beginner

Which React library is commonly used for defining routes?

React Router is the most popular library to define routes in React apps. It helps manage navigation and URL changes easily.

beginner

What does the <Route> component do in React Router?

The <Route> component tells React Router which component to show when the URL matches a path you specify.

beginner

How do you define a route for the home page '/' in React Router?

You use <Route path='/' element={<Home />} /> inside a <Routes> component to show the Home component at the root URL.

intermediate

Why do we wrap <Route> components inside a <Routes> component?

The <Routes> component groups all routes and ensures only the best matching route is shown. It manages route matching logic.

Which component from React Router wraps all route definitions?

A <Switch>

B <Routes>

C <Route>

D <Router>

wraps all components and manages which one to display.

How do you specify which component to render for a route?

A Using the 'render' prop

B Using the 'component' prop

C Using the 'element' prop

D Using the 'view' prop

In React Router v6+, use the 'element' prop with JSX to specify the component.

What happens if no route matches the current URL?

A A fallback or 'not found' route can be shown

B The first route is shown

C Nothing is rendered

D The app crashes

You can define a fallback route with path='*' to show a 'not found' page.

Which hook lets you navigate programmatically in React Router?

A useNavigate

B useRoute

C useHistory

D useLocation

useNavigate returns a function to change routes in code.

What is the correct way to import routing components in React Router v6?

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

B import { Router, Switch, Route } from 'react-router-dom';

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

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

React Router v6 uses BrowserRouter, Routes, and Route components.

Explain how to define a route for a 'Profile' page in React Router.

Think about wrapping routes and specifying the path and component.

Describe why we use the component and how it affects route matching.

Consider how React Router decides which page to show.

Practice

1. Which component is used to wrap your entire React app to enable routing?

easy

A. Link

B. Route

C. BrowserRouter

D. Routes

Solution

1. Step 1: Understand routing setup

   React Router requires a top-level component to manage routing context.

2. Step 2: Identify the wrapper component

   BrowserRouter wraps the app to enable routing features.

3. Final Answer:

   <BrowserRouter> -> Option C

4. Quick Check:

   Routing wrapper = BrowserRouter [OK]

Hint: Remember: BrowserRouter wraps the whole app for routing [OK]

Common Mistakes:

• Using <Routes> as the top wrapper
• Confusing <Link> with the router wrapper
• Using <Route> to wrap the app

2. Which of the following is the correct syntax to define a route for path '/home' rendering component?

easy

A. } />

B.

C. } />

D. } />

Solution

1. Step 1: Recall Route syntax in React Router v6+

   Routes use path for URL and element for component to render.

2. Step 2: Match correct syntax

   <Route path='/home' element={<Home />} /> uses path='/home' and element={<Home />}, which is correct.

3. Final Answer:

   <Route path='/home' element={<Home />} /> -> Option A

4. Quick Check:

   Route syntax = path + element [OK]

Hint: Use path for URL and element for component in Route [OK]

Common Mistakes:

• Using component instead of element
• Using to instead of path
• Passing component as JSX instead of element prop

3. Given this code snippet, what will be rendered when the URL path is '/about'?

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

function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route path='/' element={
Home
} />
        <Route path='/about' element={
About Us
} />
        <Route path='/contact' element={
Contact
} />
      </Routes>
    </BrowserRouter>
  );
}

medium

A. Home

B. Nothing renders

C. Contact

D. About Us

Solution

1. Step 1: Match URL path to Route path

   The URL '/about' matches the Route with path='/about'.

2. Step 2: Identify rendered element

   The matched Route renders <h1>About Us</h1>.

3. Final Answer:

   <h1>About Us</h1> -> Option D

4. Quick Check:

   URL '/about' renders About Us [OK]

Hint: Match URL path exactly to Route path to find output [OK]

Common Mistakes:

• Confusing '/' with '/about'
• Assuming default route renders for all paths
• Ignoring exact path matching

4. What is wrong with this route definition?

<Route path='/profile' component={} />

medium

A. The path should be '/profiles' instead of '/profile'

B. The prop 'component' should be 'element' with JSX

C. The component should be passed as a string, not JSX

D. Route cannot have a path prop

Solution

1. Step 1: Recall correct Route props in React Router v6+

   Routes use element prop to pass JSX, not component.

2. Step 2: Identify the error

   Using component causes the route not to render correctly.

3. Final Answer:

   The prop 'component' should be 'element' with JSX -> Option B

4. Quick Check:

   Use element, not component, for Route JSX [OK]

Hint: Use element prop with JSX in Route, not component [OK]

Common Mistakes:

• Using component prop from older React Router versions
• Passing component as string
• Omitting element or component prop

5. You want to create nested routes where '/dashboard' shows a component and '/dashboard/settings' shows inside it. Which is the correct way to define these routes?

hard

A.
}>
} />

B.
} />
} />

C.
}>
} />

D.
}>
} />

Solution

1. Step 1: Understand nested route path rules

   Nested routes use relative paths inside parent Route; child path 'settings' appends to '/dashboard'.

2. Step 2: Check each option for correct nesting

   <Routes> <Route path='/dashboard' element={<Dashboard />}> <Route path='settings' element={<Settings />} /> </Route> </Routes> correctly nests settings as child path without repeating parent path.

3. Final Answer:

   <Routes> <Route path='/dashboard' element={<Dashboard />}> <Route path='settings' element={<Settings />} /> </Route> </Routes> -> Option A

4. Quick Check:

   Nested child paths are relative, no leading slash [OK]

Hint: Nested routes use relative paths without leading slash [OK]

Common Mistakes:

• Using absolute paths in nested routes
• Defining nested routes as siblings
• Repeating parent path in child route