Node.js Interview questions are crucial in preparing for an interview with a software developer. Node.js is utilised by top companies like Netflix, LinkedIn, NASA, Trello, PayPal, Walmart, Uber, Twitter, Yahoo, eBay, and GoDaddy since programming within Node.js is faster, easier, and more efficient. The Node.js environment is more efficient and simpler, reducing development time and overall time to market.

The need for Node.js programmers is growing rapidly. These Node.js interview questions below will give you an idea of the kind of questions that you might be asked in your interview.

In this article, we have covered both the basics and more advanced Node.js questions for interviews. If you can practice the Node.js interviews, you'll definitely succeed in the next software developer interview.

Basic Node.js Interview Questions and Answers

Some employers might employ a combination of these fundamental Node.js questions for interviews based on the kind of job. Therefore, make sure you are aware of the most important subjects before the time.

1. What is Node.js? Where can you use Node.js?

This is among the most frequently requested Node.js Interview questions. Node.js is a renowned web application framework used for server-side scripting that allows you to create robust and scalable applications.

The framework is built using Google Chrome's V8 JavaScript Engine. Nide.js is covered under MIT licence and it is available for free. It extends the JavaScript API to allow for standard server-side functions. It's typically utilized for the following functions:

Development of large-scale applications, including video streaming websites single-page apps, as well as other web-based applications that are real-time.

It is perfect for applications that require a lot of data.

• Network applications
• General-purpose applications
• Distributed systems

2. What is it that makes Node.js superior to other frameworks?

It is important to consider these aspects when answering these Node.js interview questions.

Data is not buffered as it outputs content in chunks.

• Node.js allows for easy development due to its non-blocking, I/O. In contrast to other frameworks that let software developers make use of the concept of thread management Node.js is an event-driven model which allows for a short response time and fast processing.
• Node.js is based on a Chrome V8 engine, written with C++. It is extremely efficient and has continuous advancement.

The application of JS in both the front-end as well as back-end allows for faster development.

Node.js comes with a wealth of libraries and you don't have to create a new system. Furthermore, Node.js is built on Google Chrome's V8 JavaScript Engine, making the library very efficient in the execution of code.

The mechanism for events allows it to be extremely adaptable and allows the server to react in an unblocking fashion.

Its large community of open source creates excellent modules that provide new features in Node.js applications.

3. Is Node.js only one-threaded?

Node.js utilizes a single-threaded model which supports async processors. Async processing helps the application to run faster and allows it to be more scalable under the load of web pages. This is why Node.js is a single-threaded model, with event looping.

Note: If you reside in Surat and have an interest in pursuing offline courses, DecodeX offers "Best Node.JS Training Course in Surat" and "Best Laravel Training Course in Surat" that can assist you in achieving your marketing objectives.

4. What is an event loop?

In Node.js an event loop is the primary source of the callbacks that are synchronous in an application. It's an infinite loop that is waiting for tasks, then executes them and then rests until it gets the next task.

It performs tasks using an event queue when there's no task in progress, i.e., the call stack is empty.

The event loop is the one which allows Node.js to use non-blocking I/O. You should be aware that an event loop enables you to make use of callbacks and promises.

5. What is Callback in Node.js?

A function that is invoked upon completion of a task is a callback. It lets other programs be running in the background and avoids blocking. Node.js heavily uses callback since it is an Asynchronous platform. Every one of the Node APIs is designed to allow callbacks.

6. What exactly is Callback hell? What can you do to avoid them?

A problem for the JavaScript developer who tries to run multiple asynchronous tasks at the same time is referred to as callback hell.

Asynchronous functions are those that require an external activity to complete before processing a result. These asynchronous functions require the use of a callback function to address issues and process the result.

7. What are Promises in Node.js?

The term "promise" in Node.js is a placeholder for an amount that will be accessible shortly.

Promises in Node.js allow asynchronous methods to deliver values similar to synchronous methods in which the asynchronous method produces promises for the value to be delivered shortly rather than the actual value.

There are separate callbacks which are performed for failure/success as well as handling timeouts. The promises are located in three states:

• The initial or pending state.
• The state of fulfilment is a successful operation.
• The rejection of a promise indicates the failure of an operation.

8. Why do you choose promises over calls?

You should answer Node.js interview questions using an appropriate and precise explanation explaining why you'd pick either one or the other. The main reasons to choose promise over callbacks can be described in the following:

Promises can easily manage multiple asynchronous tasks, providing more error-free handling than callbacks and assisting in avoiding the unwelcome callback nightmare.

• Built-in error handling
• The coupling is very low.
• Increased accessibility

9. What are the various types of API functions?

The API functions of Node.js are divided into two categories which are:

• Asynchronous Non-blocking functions.
• Blocking, Synchronous functions.
• Blocking functions are executed in synchronization. Other code is stopped from running until an I/O situation occurs.
• Non-blocking functions run asynchronously, i.e. the program can make multiple I/O calls can be made without the execution of the program being stopped.

10. What is REPL? What is its purpose?

REPL is the abbreviation used for Reading Eval Print Loop. It is a computer-based environment like a Windows console and Unix/Linux Shell, where the user enters a command and the system then reverts to an output. It's a simple command-line tool to process Node.js expressions.

You can also discuss REPL when answering the Node.js Interview question.

• Read: It takes the input, converts it into a JavaScript Data Structure, and then stores the data in memory.
• Eval Evaluation: It evaluates and accepts the structure of data.
• Print: Prints the final result.
• Loop: The command loops, i.e., it repeats the process until you press ctrl-c two times to end.