React Router is widely used with React applications to route and navigate between the applications. In this tutorial, we will see the top React Router questions that can be asked in the interview.

Let’s discuss some common questions that you should prepare for the interviews. These questions will be helpful in clearing the interviews, especially for the frontend development or full stack development role.

1. What is React Router?

React Router is a standard library for routing in React. It enables the navigation among views of various components in a React Application, allows changing the browser URL, and keeps the UI in sync with the URL.

2. How do you install React Router?

You can install React Router using npm or yarn:

• Using npm

npm install react-router-dom

• Using Yarn

yarn add react-router-dom

3. What are the benefits of using React Router?

1. Declarative Routing: React Router provides a declarative way to define routing in your application using JSX syntax. This makes it easy to understand and maintain the routing configuration of your application.
2. Dynamic Routing: React Router supports dynamic routing, that allows you to define routes with parameters that can change based on user input or application state. This makes it easy to create dynamic and data-driven UIs.
3. Code Splitting: React Router supports code splitting that allows you to split your application into smaller chunks that are loaded on demand.
4. History Management: React Router provides a history API that allows you to programmatically navigate between different pages in your application, as well as manage browser history (e.g., go back, go forward).
5. Server-Side Rendering: React Router is compatible with server-side rendering (SSR) frameworks like Next.js, allowing you to render React components on the server and send the fully rendered HTML to the client. This can improve SEO and initial load performance.

4. Can we use React Router with server-side rendering?

Yes, React Router can be used with server-side rendering (SSR). While React Router primarily handles client-side routing, it is compatible with server-side rendering frameworks like Next.js that allows you to render React components on the server and send the fully rendered HTML to the client.

5. What is browser history in React Router?

In React Router, the browser history represents the user’s navigation actions and URL changes within a web browser. React Router provides a history object that allows programmatically manipulating the browser’s history that enable features like navigation, back and forward actions, and accessing location information.

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

function MyComponent() {
    const history = useHistory();

    function handleClick() {
        // Programmatically navigate to a new route
        history.push('/new-route');
    }
}

6. Do all routers have to be declared on a single page or can they be spread across multiple pages?

In React Router, routers can be declared across multiple pages or components within your application. It’s common to have multiple routers spread across different parts of your application, especially in larger projects or when using frameworks like Next.js for server-side rendering. Each router instance manages a specific portion of your application’s UI and navigation logic.

7. What is nested routing?

Nested routing refers to defining routes within other routes in a hierarchical manner. This is commonly used in frameworks like React Router or Next.js to organize and manage complex application structures. Nested routing is particularly useful for applications with multiple layers of content or sections that require their own routing logic.

8. What are breadcrumbs used for in React Router?

In React Router, breadcrumbs are used to show the current page’s location within the application’s hierarchy of routes. Breadcrumbs provide users with context and help them understand their current location within the application’s navigation structure, making it easier to navigate back to previous pages or higher-level sections. In complex applications with nested routes or deep hierarchies, breadcrumbs can be especially useful for users to trace their steps and backtrack if needed.

9. What are the differences between react-router-dom and react-router-native?

<NavLink to="" exact activeClassName="active">Home</NavLink>

<Route path ="/users/:userId" component ={UserComponent}/>

20. Explain nested routing in React Router.

Nested routing in React Router are used for defining routes within the components rendered by other routes, that creates a hierarchy of routes. This allows for more control over the rendering of components based on the URL hierarchy. For example, a parent component might render child components based on nested routes, that enables complex UI structures. By nesting routes, you can build applications with modular and reusable components.

21. What is the purpose of the withRouter higher-order component in React Router?

The withRouter higher-order component in React Router is used to pass the router-related props (history, location, and match) to a component that is not directly rendered by a <Route> component. This allows access to routing information and functionality within the wrapped component, that enables programmatic navigation, accessing route parameters, or reacting to changes in the URL without the need for prop drilling.

22. How do you access route parameters in React Router?

In React Router, you can access route parameters using the useParams hook or the match.params object.

Using the useParams hook (for functional components) you can extract route parameters from the URL. Here’s how you can do it:

23. Explain lazy loading with React Router.

Lazy loading with React Router are used to dynamically import components using React.lazy() and to improve the performance of your application by loading components only when needed(asynchronously). This technique splits the code into smaller bundles, reducing initial load times and optimizing resource utilization for larger applications.

24. What are route guards in React Router?

In React Router, route guards are mechanisms that control and manage navigation by preventing route transitions, executing specific actions, or performing checks before rendering a route. They are used for enforcing security policies, implementing authentication and authorization logic, or fetching data before rendering a route.

25. What is the difference between HashRouter and BrowserRouter in React Router?

This example uses the useLocation hook to access the current location object, including the search string containing query parameters. You can then parse the search string using the URLSearchParams API to extract the query parameters.

27. What are navigation guards in React Router.

Navigation guards in React Router are used for controlling and managing navigation in the application by intercepting route transitions and executing specific actions or checks before allowing the navigation to proceed. They are used to check security policies, implement complex routing logic, or provide a better user experience by handling navigation events appropriately.

28. What are the benefits of using React Router over traditional server-side routing?

1. Single-page application (SPA) experience: React Router enables smoother navigation within an application without full page reloads, resulting in a faster and more seamless user experience.
2. Improved performance: With client-side routing, React Router reduces server load and network latency, leading to faster page loads and better overall performance.
3. Dynamic routing: React Router supports dynamic URL patterns, making it easier to handle dynamic content and customize routes without server-side configuration.
4. Code splitting and lazy loading: React Router integrates well with code-splitting techniques, allowing for efficient loading of JavaScript code and resources, which improves initial load times and overall performance.

29. How do you pass props to components rendered by React Router routes?

You can pass props to components rendered by React Router routes using the render or children prop of the Route component, or by using the withRouter HOC.

Using the component prop:

<Route path="/example" component={ExampleComponent} />

Using the render prop:

<Route path="/example" render={(props) => <ExampleComponent {...props} additionalProp="value" />} />

30. What are route parameters in React Router?

Route parameters in React Router are placeholders within the route path that match specific parts of the URL. They are used to create dynamic routes by using a colon (:) followed by a parameter name. For example, /users/:userId defines a route parameter named userId, capturing any value in the URL following /users/.

31. What is the exact prop used for in React Router?

In React Router, the exact prop is used to ensure that a route is only matched if the URL matches the route’s path exactly, without any additional trailing characters. When the exact prop is set to true, React Router will only render the component associated with the route if the URL path matches the route’s path exactly.

For example, consider the following route configuration:

<Route exact path ="/home" component = {Home}/>

In this case, the Home component will only be rendered if the URL path is exactly /home. If the URL path includes additional characters, such as /home/about, the Home component will not be rendered unless the exact prop is set to true.

32. What is default route in React Router?

In React Router, a default route is a route configuration that matches any URL that doesn’t belongs to specific routes defined in the application. It serves as a fallback route which ensures that users are directed to a designated component or page when they navigate to undefined routes, typically used for error handling or displaying a fallback UI.

38. Explain the difference between server-side routing and client-side routing.

39. Explain the difference between BrowserRouter and HashRouter in React Router.

42. Explain the purpose of the history object in React Router.

The history object in React Router is a JavaScript object that represents the navigation history of the application. It allows you to programatically navigate between different URLs, manipulate the browser’s history stack, and listen for changes to the browser’s location. The main purpose of the history object is to provide a programmatic way to interact with the browser’s history API within your React Router components.

43. What is the purpose of the match object in React Router?

The match object in React Router provides information about how a component’s route matches the current URL. It contains several properties that help you access information about the route’s path, URL parameters, and other relevant details. The main purpose of the match object is to provide contextual information to the component about its route within the routing hierarchy.