20 Angular Router Interview Questions and Answers

Angular Router is a powerful routing library that allows developers to create Single Page Applications with Angular. When applying for a position that requires knowledge of Angular Router, it is important to be prepared for questions about its features and capabilities. In this article, we review some of the most commonly asked Angular Router interview questions and provide guidance on how to answer them.

Angular Router Interview Questions and Answers

Here are 20 commonly asked Angular Router interview questions and answers to prepare you for your interview:

1. What is Angular Router?

Angular Router is a routing library for Angular applications that allows you to declaratively define the routes in your application and navigate between them.

2. Can you explain how the router works in an Angular application?

The Angular router is responsible for handling navigation within an Angular application. It parses the URL of the current page and determines which component should be rendered based on that URL. The router also provides features like lazy loading, which allows components to be loaded on demand instead of all at once.

3. What are some of the common problems that can occur when using the Angular Router and how do you solve them?

Some common problems that can occur when using the Angular Router include:

-Router not working as expected: This can often be caused by incorrect configuration of the router or by using the wrong router for the version of Angular you are using.
-Router not loading components: This can be caused by a variety of factors, including incorrect path configuration, missing or incorrect component files, or problems with the component itself.
-Router not redirecting correctly: This can be caused by incorrect redirect configuration or by using the wrong router for the version of Angular you are using.

These problems can often be solved by double-checking the router configuration, making sure that all component files are present and correct, and ensuring that the correct router is being used for the version of Angular in question.

4. When should I use pathMatch instead of matcher?

PathMatch is used when you want to match the entire URL, while matcher is used when you want to match a specific part of the URL.

5. How does lazy loading help improve performance?

Lazy loading helps improve performance by loading only the modules that are needed at the moment, instead of loading all modules upfront. This can help reduce the amount of time and resources needed to load a page, and can also help improve the user experience by making pages load faster.

6. Is it possible to load multiple modules using a single route? If yes, then how?

Yes, it is possible to load multiple modules using a single route. This can be accomplished by using the loadChildren property of the route. The loadChildren property takes a function which returns a promise for an array of module factories. Each module factory will then be loaded and the resulting NgModule will be added to the route’s children.

7. What is a redirect and why would we use one?

A redirect is a way of sending a user to a different URL than the one they originally requested. This can be useful if you want to send users to a different page based on their location, or if you want to send them to a different page if the page they requested no longer exists.

8. What are guards and what’s their purpose?

Guards are used to protect routes, and they can be used to control access to a route, or to perform certain actions before a route is accessed. For example, a guard can be used to check if a user is logged in before allowing them to access a route.

9. What are resolvers and how do they work?

Resolvers are functions that can be used to pre-fetch data before the component is loaded. This is useful for ensuring that the component has all the data it needs before it is rendered. The resolver function is passed the route parameters and returns a promise that resolves to the data that the component needs.

10. What’s the difference between a wildcard route and a redirect?

A wildcard route is one where the URL can have any value in a specific location. This is often used when the URL doesn’t matter, or when the URL needs to be flexible. A redirect route is one where the URL is automatically redirected to another URL. This is often used when the URL has changed and you want to redirect users from the old URL to the new one.

11. What is a child route?

A child route is a route that is nested inside of another route. This allows for more granular control over the application’s routing and makes it easier to reuse code.

12. Why do you think it’s important to have a good routing strategy for your application?

A good routing strategy is important for any application, but it is especially important for Angular applications. This is because the Angular Router is designed to handle the loading and displaying of different Angular components based on the current URL. If your routing strategy is not well-defined, then your application may not work as intended.

13. What is the most convenient way to add routes to our app?

The most convenient way to add routes to our app is to use the Angular Router. The Angular Router is a powerful tool that allows us to easily add routes to our app. It also provides us with a lot of features that make routing easier, such as the ability to easily add wildcards to our routes and to automatically handle 404 errors.

14. How can you make sure that all required parameters are present before running a component?

By using the canActivate guard, you can ensure that all required parameters are present before running a component.

15. I want my components to run only after the data has been loaded from the backend – how can I do this with the router?

You can use the router’s “resolve” feature to achieve this. The resolve feature allows you to specify a list of dependencies that need to be resolved before the component is loaded. In your case, you would want to specify your data service as a dependency, and the router will make sure that the data is loaded before the component is instantiated.

16. How can you share data between two sibling components?

There are a few ways to share data between two sibling components in Angular. One way is to use a shared service. The service can be injected into both components, and then the data can be passed back and forth between the two components using the service. Another way is to use the Angular @Input and @Output decorators. The @Input decorator can be used to pass data into a child component from the parent, and the @Output decorator can be used to emit an event from the child component that the parent can listen for.

17. What is a named outlet?

A named outlet is a placeholder that Angular Router uses to insert the content of a child route into. By default, Angular Router will insert the content of child routes into the unnamed outlet, which is the main content area of the page. However, if you want to insert the content of a child route into a specific location on the page, you can use a named outlet.

18. How can you use the router to navigate back or forward from where you are now?

The router provides the ability to navigate back and forward through the browser’s history. You can use the router’s back and forward methods to do this.

19. What are query parameters in context with the Angular router?

Query parameters are a way to pass information to the Angular router. They are added to the URL after a question mark, and can be used to pass information to the router so that it can make decisions about what to do next.

20. Can you give me some examples of real-world routing strategies on large projects?

There are a few different real-world routing strategies that can be used on large projects. One common strategy is to use a “breadcrumb” approach, where each page in the hierarchy is represented by a breadcrumb trail. Another strategy is to use a “tree” approach, where the hierarchy is represented by a tree structure. Finally, a “flat” approach can also be used, where the hierarchy is represented by a flat list of pages.