Node.js interview questions are essential for preparing for a software developer interview. Node.js is used by top companies such as Netflix, LinkedIn, NASA, Trello, PayPal, Walmart, Uber, Twitter, Yahoo, eBay, and GoDaddy because programming in the Node.js environment is faster, easier, and reduces development time and overall time-to-market.
The demand for Node.js programmers is increasing at an alarming rate. The Node.js interview questions listed below will familiarize you with the types of questions you may face during your interview. In this article, we covered both basic and advanced Node.js interview questions. If you practice these Node.js interview questions, you will undoubtedly ace your next software developer interview.
Having trained over 10,000 software engineers, we know what it takes to crack the toughest tech interviews. Our alums consistently land offers from FAANG+ companies. The highest ever offer received by an IK alum is a whopping $1.267 Million!
At IK, you get the unique opportunity to learn from expert instructors who are hiring managers and tech leads at Google, Facebook, Apple, and other top Silicon Valley tech companies.
Want to nail your next tech interview? Sign up for our FREE Webinar.
This article will look at the Node.js interview questions that you may expect during software developer interviews.
Here's what we'll cover:
Some employers may use a combination of these basic Node.js interview questions depending on the job type. So, ensure that you know the important topics ahead of time.
You must consider the following factors while answering such Node.js interview questions:
Node.js employs a single-threaded model that supports async processing. Async processing enables the application to perform better and makes it more scalable under web loads. Thus, Node.js has a single-threaded model with event looping.
In Node.js, an event loop is responsible for all the asynchronous callbacks in an application. It is an endless loop that awaits tasks, executes them, and sleeps till it receives the next tasks.
It executes tasks from the event queue only when there is no ongoing task, i.e., the call stack is empty. It is the event loop that allows Node.js to have non-blocking I/O. You must know that the event loop allows you to use callbacks and promises.
A function that is called after a given task is a callback function. It allows other code to run meanwhile and prevents any blocking. Node.js heavily relies on callback as it is an asynchronous platform. All Node APIs are written to support callbacks.
A promise in Node.js is a placeholder for a value that will be available in the future. Promises in Node.js allow asynchronous methods to return values like synchronous methods wherein the asynchronous method returns a promise for the value in the future instead of the final value. They have separate callbacks that would be executed for success/ failure and handling timeouts. Promises fall in the following three different states:
You must answer such Node.js interview questions with a relevant yet precise reason explaining why you would choose one over the other. The reasons for selecting promises over callbacks are as follows:
The API functions in Node.js are of two types, namely:
Blocking functions execute synchronously. Every other code is blocked from running until an awaiting I/O event occurs.
Non-blocking functions execute asynchronously, i.e., multiple I/O calls can be performed without the program's execution being halted.
REPL is the abbreviation for Reading Eval Print Loop. It represents a computer environment similar to a Windows console or Unix/Linux shell wherein a command is entered, and the system reverts with an output. It's an easy-to-use command-line tool for processing Node.js expressions.
You can also elaborate on REPL while answering this Node.js interview question.
These were the most commonly asked Node.js interview questions. Scroll through the following section for some advanced Node.js interview questions for your tech interview prep.
Here are a few advanced Node.js interview questions and answers for senior positions. If you're interviewing for a position as a senior software developer, practice these questions to ace the interview.
This is one of the most common Node.js interview questions to gauge your knowledge of vital topics in Node.js. Piping in Node.js is the mechanism that connects the output of one stream to another, i.e., it connects multiple streams. It retrieves data from one stream and passes the output to another stream.
Node.js streams are instances of EventEmitter. You can use them to work with streaming data in Node.js, especially for handling and manipulating streaming large files (such as videos and mp3) over the network. Streams use buffers for temporary storage. There are four main types of streams.
A middleware function has access to the response object, request object, and the next middleware function in the application's request-response cycle. A variable named next denotes the next middleware function. Middleware finds usage in between your request and business logic. You can also write your own middleware for a specific use case. The primary tasks that the middleware functions perform are:
A reactor pattern is a pattern for non-blocking I/O operations generally used in any event-driven architecture. It has two components:
Exit codes of Node.js provide an idea of the reason behind code termination. Some exit codes are as follows:
Node.js applications do not use multiple core systems. Instead, they run on a single processor. In Node.js, the cluster mode helps startup multiple node.js processes, thus having multiple instances of the event loop.
When you use a cluster in a Node.js app behind the scenes, there are numerous node.js processes created, but there is also a parent process called the cluster manager. A cluster manager monitors the health of the individual instances of the application.
WASI stands for the WebAssembly System Interface. It is a capability-oriented set of APIs built to standardize the sandboxed execution of WebAssembly modules outside of browsers.
WASI was introduced with the idea in mind that it is possible to use the underlying operating system via a collection of POSIX-like functions and further enable the application to use resources more efficiently and features requiring system-level access.
You must practice the following Node.js coding interview questions to gear up for your next tech interview.
Here are some sample Node.js technical interview questions for you to practice. Preparing answers to these questions can help you ace your tech interview.
Q1. Does Netflix include Node.js interview questions for backend developer interviews?
If you are preparing for a backend developer position at Netflix, you must thoroughly study the crucial topics of Node.js. Netflix uses it to streamline the development and cut the build times while increasing the level of customization of its UIs for every user.
You should be prepared for both fundamental and advanced Node.js interview questions for your Netflix interview.
Q2. Are Node.js interview questions important for front-end developers?
Node.js gained popularity as a backend framework. Nowadays, the Node.js front-end framework has become a popular choice for building quick, efficient network applications for many top tech companies. If you are preparing for a front-end developer interview, you must study node.js for your interview prep.
Q3. How long would it take to learn Node.js?
Register for our technical interview webinar to get ready for an upcoming software engineer or software developer interview. At Interview Kickstart, we’ve trained over 10,000 engineers to land lucrative offers at the biggest tech companies. Our instructors, who are FAANG+ hiring managers, know what it takes to nail tough tech interviews at top technology companies.
Register for our FREE webinar to learn more.