FullStack Developer Interview Questions

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When we talk of Full-stack developers, we refer to individuals who work with the front end, back end, server side, or client-side. Generally, Full-stack developers have many powerful coding skills in different niches. Note that a Full-stack developer course is quite marketable with many companies looking to hire these individuals.

Are you wondering want type of questions you may come across as a Full-stack developer? If yes, then you are in the right place. Why? Because this article explains some of the top interview questions you might come across and their answers. Check out the information below.

What is your favorite programming language as a Full-stack developer, and why?

From the definition of a Full-stack developer, you can tell that these individuals deal with many coding languages. As a result, it is quite difficult to prefer one language more than the others since it requires multiple languages. A Full-stack developer loving one language more isn’t considered a good signal. Generally, you will find that some of these experts do have a few coding languages they love and which they commonly use to program. However, it is no secret that the best Full-stack developer is an expert who can demonstrate excellent skills in various programming languages, including the most basic such as HTML, Python, CSS, and many more.

How do you ensure that you have updates on new trends in the technological field?

It is no secret that technology changes every day. As a result, Full-stack developer needs to keep themselves updated on all the new things. A good Full-stack developer is part of popular community meetups that help them keep up with the latest trends. Also, the community meetups offer developers a chance to share personal projects and have experts’ input on the matter.

What is the most important quality a Full-stack developer must develop?

A high-quality Full-stack developer needs one key quality: competence in different coding languages, especially basic Python, CSS, and HTML. Why? Because knowing coding languages are the foundation of Full-stack development. Also, the experts must have coordination skills to work with a team and deliver excellent results.

What is pair programming?

Pair programming is a revolutionary core programming method that involves two experts working on a similar terminal. In this process, you involve two people, a driver and a navigator. The driver is in charge of typing the codes while the navigator reviews the programs.

In the industry, what do experts refer to as CORS?

CORS, Cross Origin Resource Sharing, refers to accessing different web resources on various domains. Using CORS, Full-stack developers can integrate all the web scripts with the domain’s external content. As a result, the CORS leads to good integration among web services.

Relating to past experiences, Can you explain how you dealt with a colleague’s inefficient code?

A good Full-stack developer must have the guts to point out flaws from their colleague’s code comfortably. Other than pointing out the flaws, it would be best if you gave positive feedback so that you can comfortably work together with your teammates at work.

What coding languages are you comfortable with as a Full-stack developer?

As a Full-stack developer, the basic languages you need to know are HTML, CSS, and JavaScript. Since they are the basic requirements, a stable developer must state these languages. Note that you can mention other languages you are comfortable with, like Python, Ruby, PHP, and many more.

What is DevOps?

DevOps is currently among the top technological evolutions. It refers to communicating and working together with software developers and other experts in the industry. The main purpose of this practice is to deliver the required software in time and reduce the rate of failure.

What is continuous integration?

Continuous integration, CI is automating code integration between various contributors when doing a single software project. It is one of the key practices that DevOps needs to develop since they have to frequently merge different programs from various developers to form a central repository code to build and run tests. Continuous integration assists the developers in detecting the problems easily, and everyone can monitor the program’s operation.

What factors should you consider for the success of continuous integration?

Here are some things that contribute to a successful continuous integration process

  • Maintain the central repository
  • Automation of the build
  • Allow self-testing of the build
  • Ensure that every developer commits daily to the baseline
  • Ensure that the build is fast
  • Test the operation of the code in a well-stimulated environment
  • Ease the process of getting updates
  • Ensure that all the people can easily assess the latest updates
  • Automate the code deployment process

What do you refer to as Callback Hell?

It is a function that callback various parameters. This feature is important when dealing with multiple functions chained together, and you need to callback one of them.

Explain multi-threading

You can improve the performance of your CPU using multi-threading. Under this setting, your program can comfortably manage various requests using one user. Also, it can handle multiple users during the same period. This feature is excellent for improving a program’s performance.

As a developer, how can you reduce the loading time of your web application?

You can minimize the load time by using various methods such as reducing the HTTP requests, image optimizations, redirects reductions, eliminating unnecessary plugins, and browser caching enabling.

  • Optimization and compression of images: Images are perfect for enhancing web pages’ appearance and improving the quality of the content. Large photos will lead to a delay in the web loading time. So, if you need to reduce the loading time, the easiest way involves compressing and optimizing the images.
  • Redirects reductions: Many redirects can lead to increased loading time. Why? Because every redirect of a page prolongs the response process and HTTP request. Redirects are okay when they are necessary but when unnecessary, avoid them.
  • Enable browser caching: Browser caching is a form of caching that helps improve web page loading speeds. When using this technique, your browser stores various information, including images, files, and stylesheets: As a result, it isn’t necessary to reload the page when you need to visit the page.
  • Eliminate unnecessary plugins: Plugins can never be alike, and having many unnecessary plugins in your web application results in excessive bloating, leading to a lot of loading time. Besides, outdated plugins without maintenance can lead to security breaches. Therefore, it is good to minimize the plugins on your site and delete all the unnecessary plugins.

What is long polling?

The long polling technique involves a development pattern that exceeds data from your server to the clients. It works in a way that when a client requests something, and it is currently unavailable, the server waits and gives the clients a response instead of delivering empty requests.

Explain an application server

It refers to an application that allows the developers to design and maintain both the client-side and server-side applications. In other words, it is a server responsible for hosting applications.

What is Referential Transparency?

This technical term references functional programming. It refers to a situation in a program where a value can comfortably replace an expression without altering the final result of the code. In other words, you can substitute a term in a program with a value and still maintain the final output of the program.

What is Inversion of Control?

It is a technical term used broadly by software developers to define a programming pattern used to decouple components and layers in a system.

What is REST development?

REST, Representational State Transfer, is an architectural style in software development that guides the design and the development of the software’s architecture in the WWW, World Wide Web. Besides, it explains constraints in software architecture and how a system should behave.

Explain GraphQL

It refers to syntax or a set of rules that defines ways of asking for data. Usually, it is quite popular when loading data from the server to the client. Besides, clients can use this syntax to describe the data they need while allowing the system to gather all the necessary data from multiple sources. GraphQL uses the type system to define data. In other words, they make the APIs flexible, user-friendly, and fast.

What is the difference between REST and GraphQL?

Both REST and GraphQL are API design settings that undertake a similar function: data transmission through various internet protocols. However, the two work differently, such that GraphQL is a query language while REST is an architectural style.

Which one is better, REST or GraphQL?

Generally, the two options take up a similar function, data transmission. However, we have many experts comparing the two depending on how they undertake tasks. GraphQL is the latest technology, with many people recommending it thanks to its functionality. The syntax has gotten rid of the under-fetching and over-fetching data transmission issue; hence, clients only request the necessary information. As a result, the query language is user-friendly and faster compared to REST. The latter tends to define the resources’ size using the server. Note that the two options are quite good, and there is no chance for GraphQL to replace REST.

What are the pros and cons of using the “use strict” statement?

The “use strict” statement refers to activating the strict mode to individual functions and scripts in the technological industry. When talking of strict mode, it means that you are opting in a restricted form in JS.


  • You can’t create global variables under this mode by mistake
  • This mode comfortably delivers assignments that wouldn’t be acceptable under the normal mode
  • It makes it possible to get rid of undeletable properties under the standard form
  • The function parameter term is unique
  • Using the term “this” is undefined under the global environment
  • The mode is quite keen and often gather standard coding bloopers
  • The strict mode doesn’t allow the operation of confusing features


  • Many features that many programmers are quite used to are absent under this strict mode
  • You can’t use the two popular functions function. Caller and function. Arguments
  • Connecting web scripts that use different strict modes may cause operation issues

What is Prototype Inheritance in JavaScript?

In implementing inheritance in coding languages such as C#, C++, and Java, developers mainly begin by class creation. A class is a set of things that have the same attributes. After class creation, the developers create objects or extend the classes.

However, in JavaScript, things are a bit different since it doesn’t have the class concept. You kick off by creating an object, then extend them to create new objects. In JS, every object features a prototype. And the inheritance deals with prototypes. Upon message deliverance in an object, the programming language first tries to derive a property from the object. However, if the property is absent, then JS sends the message to the prototype. And this kind of inheritance style is what we call the prototype chain of prototype inheritance.

In JavaScript, constructor functions are the best options during prototype inheritance. Note that constructors are closely related to regular functions. However, they are commonly used with new keywords. Normally, developers use a constructor to develop similar objects that feature the same methods and properties.

What are the cons of GraphQL?

GraphQL is a popular query language that developers use for data transmissions. And over the last couple of years, its popularity has kept rising. However, there is nothing good without its flaw. The common disadvantages of using the syntax include:

  • If you want to use GraphQL, then you must learn how to set it up. Note that the language keeps evolving; hence there are changes all the time, and developers need to keep up with the updates
  • Developers need GraphQL endpoint on the server
  • The queries require more space compared to REST
  • Your serve is prone to perform more processing to deliver the request and verify the information

Define event loop

The node in JavaScript is an application that promotes concurrency using callbacks and event concepts. Event loop helps Node.js to undertake non-blocking functions despite JS being a single-threaded language. In other words, it sends events in a queue being the processing takes place.


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