15 Advanced Node JS Interview Questions and Answers

The EventEmitter is a class that facilitates communication/interaction between objects in Node.js. The EventEmitter class can be used to create and handle custom events. These objects are modules, functions, strings and object itself as explained below. Node.js runs in a single process and the application code runs in a single thread and thereby needs less resources than other platforms. Error throwing – well-establish pattern, in which a function does its thing and if an error situation arises, it simply bails out throwing an error. Also wrapping the async calls in try/catch won’t help because the errors happen asynchronously.

After completing this step, they are finally removed from the buffer. Unlike the readFile process, the createReadStream process is effective for the processing of large files. The readFile() process is a fully buffered process that returns the response only when the complete file is pushed into the buffer and is read. This process is called a memory-intensive process, and in the case of large files, the processing can be very slow. In Node.js, an EventEmitter is a class that includes all the objects capable of emitting events.

Skills and competencies that you need in a Node.js developer

This thread is responsible for completing a particular blocking request by accessing external resources, such as computation, database, file system, etc. This section will provide you with the Basic Node.js interview questions which will primarily help freshers. We have compiled a comprehensive list of common Node.js interview questions that come up often in interviews and the best ways to answer these questions.

If you need a database that can handle large amounts of unstructured data and prioritize scalability, MongoDB might be a better choice. On the other hand, if you require a fully ACID-compliant database with a proven https://wizardsdev.com/en/vacancy/middle-nodejs-developer-3/ track record, PostgreSQL may be a better fit. Overall, OAuth2.0 provides a secure and convenient way for users to share their resources with third-party applications, without compromising their credentials or data.

Q. How are event listeners created in Node.JS?

Note that this code snippet uses the hashing capabilities, and it uses the “pbkdf2” function from the “crypto” module. Describe the projects you have and how the contribution of the Node.js developer will help your organization. Explain whether you have development projects, maintenance projects, or both.

It’s vital to understand all the basics of Node.js itself – how the event loop works, why you should avoid synchronous methods and more. Working with Node.js is a lot about handling APIs and the framework you should be familiar with is express.js. That’s why you should definitely brush up on error handling in express.js and the mechanics of the middleware. Any asynchronous method expects one of the arguments to be a callback. The full callback argument list depends on the caller method, but the first argument is always an error object or null. When we go for the asynchronous method, an exception thrown during function execution cannot be detected in a try/catch statement.

Node.js Interview Questions and Answers for 2023

Payload – Contains the claims that provide information about a user who has been authenticated along with other information such as token expiration time. The main process assigns the port to a child process and child process itself listen the port. Reading large log files and writing selected parts directly to another file without downloading the source file.

It is important to detach an event Listener once its no longer needed to avoid memory leaks. Functions like .removeListener(), .removeAllListeners() enable the removal of listeners from the listeners Array. // When the event “listenerOne” is emitted, both the above callbacks should be invoked. It facilitates an event-driven approach wherein I/O and other activities are performed using callback-based notifications. It allows the CPU and other resources to be used simultaneously while still performing I/O operations, thereby resulting in efficient use of resources and network. It is an inbuilt global object that is an instance of EventEmitter used to get information on current process.

What is an error-first callback in Node JS?

I likened real-time updates to a messenger app where you can see when someone is typing and receive messages instantly. Then, I explained that we would be using Node.js and WebSocket technology to achieve this in our web application. When answering this question, remember to show empathy for the non-technical stakeholder and how you modified your communication style to accommodate their understanding. It’s essential to provide a specific example that demonstrates your ability to adapt your communication and ensure a mutual understanding of the issue at hand. As our collaboration progressed, I became more comfortable working with their technical expertise and was able to contribute valuable insights from my server-side perspective.

They include types of scopes, closures, and differences between various types of variable declarations as well as creating all kinds of functions. All of this has a great impact on the quality of the code you write. Middleware functions that return a Promise will call next when they reject or throw an error.

Building Web Application Using Spring Framework

As a Node JS developer, my expertise was mainly in server-side programming. However, on that project, I had to collaborate with a front-end developer who was experienced in React and a designer who had a strong background in user experience . When answering this question, avoid providing a generic or overly broad response. This question is aimed at testing your knowledge of a specific security concern – code injection attacks – and your ability to provide practical solutions to prevent them. As a hiring manager, I want to know that you’re aware of this risk and have experience implementing measures to protect Node.js applications from such attacks. When discussing code injection prevention, be sure to mention techniques like input validation, parameterized queries, and proper use of security libraries.

• The spawn() method does not have access to the same variables and functions as the existing process, but it runs faster than the fork() method.
• The event loop is the processing model’s beating heart in Node.js.
• As an interviewer, what I like to see here is how you handle challenging situations and how adept you are at using Node.js to solve problems.
• It is believed that more performance and scalability can be achieved by doing async processing on a single thread under typical web loads than the typical thread based implementation.

An event can be generated by the user, by the system, or by the program itself. Exit codes are a collection of specific codes whose function is to complete a specific process. Examples of exit codes are fatal error, unused, internal JavaScript evaluation failure, etc.