20 Single Page Application Interview Questions and Answers

A Single Page Application (SPA) is a web application or website that loads a single HTML page and all associated resources (such as JavaScript, CSS, and images) required to display content. SPAs are typically faster and easier to use than traditional multi-page web applications because they eliminate the need to reload the page each time the user interacts with the app. If you’re interviewing for a position that involves SPAs, you should be prepared to answer questions about your experience and knowledge of this type of application. In this article, we’ll discuss some common SPA interview questions and how you can answer them.

Single Page Application Interview Questions and Answers

Here are 20 commonly asked Single Page Application interview questions and answers to prepare you for your interview:

1. What is a Single Page Application?

A Single Page Application is a web application that loads a single HTML page and then dynamically updates that page as the user interacts with the app. The advantage of this approach is that it can provide a smoother, more responsive user experience since the entire page doesn’t need to be reloaded each time the user performs an action.

2. Can you name some popular single page applications?

Some popular single page applications include Gmail, Google Maps, and Facebook.

3. What are the benefits of using SPA in web application development?

Single page applications offer a number of benefits over traditional multi-page web applications. They are generally faster and more responsive, as there is no need to reload the page every time the user interacts with the app. They are also more scalable, as the same codebase can be used for both mobile and desktop versions of the app. Finally, SPAs tend to be more user-friendly, as they provide a more seamless and uninterrupted experience for the user.

4. What are the limitations of using SPA in web application development?

One of the potential limitations of using SPA is that it can make your web application more complex and difficult to develop and maintain. This is because SPAs typically require a lot of JavaScript code in order to function properly. This can make your web application more difficult to debug and test, and can also make it more difficult for new developers to understand and work on your code. Additionally, SPAs can also be more difficult to optimize for search engine optimization (SEO) since the search engines may have difficulty crawling and indexing the JavaScript-heavy code.

5. How does SPA work?

Single Page Application works by loading a single HTML page and then dynamically updating that page as the user interacts with the application. This means that the server only needs to send the initial HTML page to the client, and then the client can handle all further interactions with the application. This can make SPAs much faster and more responsive than traditional web applications.

6. What’s the difference between SPA and MPA?

MPA stands for Multi-Page Application, while SPA stands for Single-Page Application. The main difference between the two is that an MPA will have multiple pages that the user can navigate to, while an SPA will have only a single page. This means that all of the content for an SPA must be loaded onto the single page, which can make it more complex to develop and manage. However, it also means that SPAs can be faster and more responsive for users, since they do not need to wait for new pages to load.

7. What components make up an SPA?

The three main components of an SPA are the model, view, and controller. The model is responsible for managing the data of the application, the view is responsible for displaying the data to the user, and the controller is responsible for handling user input and updating the model accordingly.

8. What programming languages can be used to develop SPAs?

SPAs can be developed using a variety of programming languages, including but not limited to: HTML, CSS, and JavaScript.

9. What frameworks can be used for developing SPAs?

There are many frameworks that can be used for developing SPAs, but some of the most popular ones include AngularJS, ReactJS, and VueJS.

10. Is it possible to build an SPA that stores all its data locally on the client-side? If yes, then how?

Yes, it is possible to build an SPA that stores all its data locally on the client-side. This can be accomplished by using local storage, IndexedDB, or a similar client-side storage solution.

11. Is it possible to convert an existing website into an SPA? If yes, then how?

Yes, it is possible to convert an existing website into an SPA. The process generally involves re-writing the website’s code so that it is more modular and can be loaded dynamically, rather than having to reload the entire page every time a user navigates to a new section. This can be a significant undertaking, but the end result is a website that is much faster and smoother to use.

12. What do you understand about progressive enhancement?

Progressive enhancement is a strategy for web development that focuses on providing a basic level of functionality and content to all users, regardless of browser type or capabilities. Then, additional layers of functionality and content are added for users with more advanced browsers. This ensures that everyone can access the basic content and functionality of a web site, while also providing a richer experience for those with more advanced browsers.

13. What is AJAX? How does it relate to SPAs?

AJAX is a technique used for making asynchronous requests to a server in order to update parts of a web page without having to reload the entire page. This is often used in SPAs in order to make it possible to update the page without having to reload the entire thing every time something changes.

14. What is SEO? How does it affect SPAs?

SEO is short for “Search Engine Optimization”. It is the process of optimizing a website to rank higher in search engine results. This is important for SPAs because, if a SPA is not optimized for SEO, then it is likely that it will not show up in search engine results at all. This means that potential users will never even know that the SPA exists.

15. What is PWA or Progressive Web Apps?

Progressive Web Apps are web applications that are designed to look and feel like native apps, but they are actually just web pages or web apps that use modern web technologies. They are designed to be fast, reliable, and engaging, and they can work offline and be installed on your device.

16. What is the best way to structure your code when building an SPA?

When building an SPA, it is important to keep your code well organized and modular. This will make it easier to manage your code as your application grows. A good way to do this is to use a framework such as AngularJS. This will give you a structure to follow and will help keep your code organized.

17. What are the advantages of using SPA over traditional websites?

SPAs offer a number of advantages over traditional websites, including improved performance, increased engagement, and a more immersive user experience. SPAs are also more flexible and can be adapted more easily to different screen sizes and devices.

18. What steps should you follow while designing an SPA?

The steps to designing an SPA are as follows:
1. Plan the overall structure of the application and decide which pages will be static and which will be dynamic.
2. Create a skeleton for the application, including the necessary HTML, CSS, and JavaScript files.
3. Implement the basic functionality of the application, including routing, data binding, and any other necessary features.
4. Test the application and make sure it is functioning properly.
5. Deploy the application to a web server.

19. What tools and services are available for testing SPAs?

There are a few different options available for testing SPAs. One option is to use a headless browser, which is a browser that can be controlled programmatically without a graphical user interface. This allows you to automate tests and run them in a real browser environment. Another option is to use a browser plugin or extension, which can provide some limited testing capabilities. Finally, you can also use a service like BrowserStack or SauceLabs, which provides cloud-based testing services that can be used to test SPAs.

20. What are some open source SPAs that you have come across?

Some popular open source SPAs are AngularJS, ReactJS, and VueJS.