The Top 15 React Router Interview Questions and Answers in 2023

React Router is one of the most popular and widely used routing libraries for React applications. As more and more companies adopt React for front-end development, having a strong grasp of React Router is becoming an essential skill for front-end developers.

In this article, we will go over the top 15 React Router interview questions that you should prepare for when interviewing for React developer roles. Whether you are a junior developer looking for your first React job or a senior engineer exploring new opportunities, being able to answer React Router questions confidently will give you a leg up in the interview process.

Q1: What is React Router and why is it useful?

React Router is a routing library for React that allows developers to implement dynamic routing in a web app Some key benefits of using React Router include

• It enables the creation of single page web applications with different views/components that can be displayed based on the URL without needing a full page refresh. This results in faster page transitions and better user experience.

• It allows developers to pass props and context to components for the active route, making it easy to render UIs based on the current URL.

• It provides hooks like useHistory and useLocation that enable navigation via push/replace methods. This avoids the need to directly manipulate the browser history.

• It supports parameters in routes out of the box, making it easy to pass data across routes.

• It integrates well with other React libraries and is extensible via third-party routing packages.

Overall, React Router is a seamless way to handle routing in React apps, leading to its immense popularity.

Q2: How is React Router different from conventional routing?

Some key differences between React routing and traditional routing

• Single page app: React Router enables a single page web app to have multiple views/components that render based on the URL path, without full page refreshes. Traditional routing relies on multiple HTML pages for each view.

• Component based: In React Router, views are composed as React components that are dynamically rendered when their path is matched. Traditional routing uses static HTML files.

• Programmatic navigation: React Router provides hooks like useHistory to navigate programmatically vs relying on anchor tags.

• URL params: It’s easy to parse URL parameters with React Router vs having to manually parse the URL in traditional routing.

• Performance: By avoiding full page refreshes, React Router enables faster page transitions and better overall performance.

Q3: How do you pass parameters through a React Router URL?

There are a couple ways to pass parameters through a URL with React Router:

1. Using route path params like /path/:paramName and accessing the params via useParams() hook.

2. Using search query strings like /path?param=value and accessing via useLocation() hook.

Here is an example:

// Route path with :id parameter <Route path="/product/:id" />// Access param via useParams hookconst { id } = useParams(); // Query string with "sort" param<Link to="/products?sort=asc" />  // Access search params via useLocation hookconst { search } = useLocation();const sort = new URLSearchParams(search).get('sort');

Q4: How do you navigate programmatically in React Router?

There are a couple approaches to programmatically navigate to routes in React Router:

1. Using the useHistory hook to access the history instance and calling push() or replace() methods:

import { useHistory } from 'react-router-dom';const history = useHistory(); history.push('/new-path'); // new entry in history stackhistory.replace('/new-path'); // replaces current entry

1. Using the <Redirect> component:

<Redirect to="/somewhere/else" />

The useHistory hook gives the most flexibility for navigation in components. <Redirect> is useful for conditional redirects i.e. after form submission.

Q5: How do you handle 404s (not found routes) with React Router?

A few ways to handle 404s or not found routes with React Router:

1. Have a catch all 404 route that matches any unknown path:

<Switch>  <Route exact path="/" />    // Other routes    <Route path="*">    <NotFound />   </Route></Switch>

1. Use <Redirect> to redirect 404s to a known route:

<Switch>  <Route exact path="/" />  // Other routes  <Redirect to="/" /> </Switch>

1. Render a <NotFound> component for undefined match prop:

const MyRoute = ({ match }) => {  if (!match) {    return <NotFound />  }  // ...}

Having a dedicated 404 route is usually preferable, to avoid redirect loops.

Q6: How do you pass props to components rendered by React Router?

Some ways to pass props to route components:

• Specify props on the <Route> component to pass them to the rendered component:

<Route   path="/products"  render={(props) => <Products {...props} extraProp="foo" />}/>

• Use the <Route> children prop:

<Route path="/products">  <Products extraProp="foo" /></Route>

• Access route props via hooks like useRouteMatch() and spread into rendered component:

// Get route propsconst { path, url } = useRouteMatch();// Spread props into rendered component  <ProductDetails {...{ path, url }} />

Q7: How do you implement nested routes with React Router?

React Router makes it straightforward to have nested route configuration using the <Switch> and <Route> components.

Some ways to implement nested routes:

// App.js<Switch>  <Route exact path="/" />   <Route path="/users" component={Users}/>  <Route component={NoMatch}/> </Switch>// Users.js<Switch>  <Route exact path="/users" component={UsersIndex}/>    <Route path="/users/add" component={AddUser}/>  <Route path="/users/:id" component={UserProfile}/></Switch>

The <Switch> component ensures only the first matched <Route> is rendered.

Nested routes are commonly rendered in the parent component to keep route config in one place.

Q8: How do you link between pages in React Router?

The React Router <Link> component is used to create links between pages instead of anchor tags:

// App.js<Link to="/products">Products</Link> // Renders anchor tag with correct href<a href="/products">Products</a>  

Benefits of using <Link>:

• It activates the correct route upon click.
• Automatically applies active class to add styling.
• Has access to route state and props.
• Prevents full page refresh like anchor tags.

Q9: How do you get access to the history instance with React Router?

There are a couple ways to get access to the router history instance in React Router v6:

1. Use the useHistory hook:

import { useHistory } from 'react-router-dom';const history = useHistory();

1. Access it via the Router component props:

<Router history={customHistory}>  {/* ... */}</Router>const customHistory = routerProps.history;

The history instance enables navigation via push/replace methods. In most cases, the useHistory hook is the simplest way to use it.

Q10: How do you set up React Router with server-side rendering?

To integrate React Router with server-side rendering, here are the key steps:

1. Use a <StaticRouter> component instead of <BrowserRouter> on the server.

2. Pass the request URL to render correct initial route.

3. Use router state to fetch data before rendering.

4. Return router state along with HTML