• ( )

25 Most Asked Node JS Interview Questions

Here are sample answers to five Node.js interview questions about skills. Refer to the answers provided when reviewing your candidates’ responses. Candidates should know that streams can help developers accomplish a variety of tasks, like handling network communications and easily managing end-to-end information exchanges.

We use Node.js most frequently in IoT, Complex SPAs, real-time chats, real-time collaboration tools, microservices architecture, and streaming applications. Modulus is various commands used in node js to perform tasks like addition, subtraction, division, multiplication, etc. Node.js do provide a simple TCP based protocol and debugging client that comes built-in. In order to debug your JavaScript file, you can use the below debug argument followed by js file name that you want to debug. If the project is in the production stage, Node.js promotes the convention of making use of NODE_ENV variable to flag it.

Technical Interview

Moreover, Node.js has an optimized design which utilizes both JavaScript and C++ to guarantee maximum performance. JavaScript executes at the server-side by Google Chrome v8 engine. And the C++ lib UV library takes care of the non-sequential I/O via background workers.

It is one of the most important aspects of Node.js and the reason behind Node.js have non-blocking I/O. Since Node.js is an event-driven language, you can easily attach a listener to an event and then when the event occurs the callback will be executed by the specific listener. Whenever functions like setTimeout, http.get, and fs.readFile are called, Node.js executed the event loop and then proceeds with the further code without waiting for the output. Once the entire operation is finished, Node.js receives the output and then executes the callback function.

Top Node JS Interview Questions to Practice

The main benefit of keeping Express ‘app’ and ‘server’ separate is faster execution of testing. We can test API in-process without the need for handling network calls. Additionally, developers can deploy an API to varied network conditions. In Node.JS, fork helps in the creation of a fresh instance of the V8 engine. In the case of other frameworks, fork enables the spawning of child processes.

Node.js Developer interview questions

The Promise wraps the fs.readFile() operation, and when the operation completes, it either resolves with the file content or rejects with an error. We can then use .then() to handle the successful result and .catch() to handle any errors, making the code more readable and organized. Middleware functions in Node.js help in the execution of all types of codes.

Q14: How do you debug Node.js applications? ☆☆☆

At we hire the best developers in Eastern Europe countries. I wanted to share with you our NodeJS/Fullstack job interview questions. Another reason why these basic Node.JS interview questions are so important is because you can check the basic level of Node.JS knowledge. After you evaluate the level of qualification of the candidate, you can decide what type of difficult questions you should give the developers later.

Node.js Developer interview questions

Node.js is a server-side JavaScript runtime environment built on top of the V8 JavaScript engine, the same engine that powers Google Chrome. It makes Node.js very fast and efficient, as well as highly scalable. The V8 engine, developed by Google, is open-source and written in C++. V8, unlike the other engines, is also utilized for the popular Node.js runtime.

Question 7: What is event-driven programming?

It delivers information to npm to identify and manage project dependencies. We can perform complex computation, I/O operations, and blocking asynchronously with the help of the Event loop. We can avoid callback hell in Node by using Async.js, Async-Await, and Promises.

Node.js Developer interview questions

If the session ID is not valid or missing, appropriate status codes (401 or 403) are sent in response, indicating unauthorized access. Authentication is the process of verifying the identity of a user, typically by providing credentials (such as username and password). Once the user is authenticated, they receive an authentication token, which is used to identify them in subsequent requests. The package will be downloaded and saved to the node_modules directory in your project. Core modules are modules that are included by default in Node.js, and you can use them without installing any additional packages.

Define the concept of the test pyramid. Explain the process to implement them in terms of HTTP APIs.

The developer doesn’t need to use imports or require statements to access and use these objects in an application. Instead, they can declare them with a value and access them anywhere in a program. A stream is an object in Node.js that developers often use to read or write data continuously. Domain error handlers are not a substitute for closing down a process when an error occurs.

  • The http module provides an API for creating and interacting with HTTP servers and clients.
  • In summary, GraphQL provides more flexibility and efficient data loading but comes with increased complexity and a steeper learning curve.
  • The package.json file in Node.js is the heart of the entire application.
  • If a worker process dies (‘exit’ event), the master process replaces it with a new worker using cluster.fork().
  • This will install the express package and add it as a dependency in the package.json file.

Non-blocking in Node.js means that the program can continue to execute other code even while waiting for I/O operations to complete. Node.js developers can build various applications, including web applications, chat applications, real-time applications, streaming applications, APIs, and desktop applications, etc. If you want to globally install a dependency, you can use the -g flag.