Node Js Interview Questions And Answers
node.js Interview Questions and Answers
Node Js Interview Questions And Answers
In a Node.js interview, candidates are typically asked questions to assess their understanding of JavaScript, Node.js core functionalities, event-driven architecture, asynchronous programming, package management using npm, handling errors, RESTful APIs, and database integration with frameworks like Express and MongoDB. Answers should demonstrate proficiency in creating server-side applications, working with streams, understanding callback functions and Promises, optimizing performance, securing Node.js applications, and familiarity with common Node.js modules. Additionally, candidates may be asked about debugging techniques, module exports and require(), event loop, clustering, and real-time applications using WebSockets. It is crucial for candidates to showcase their problem-solving skills, experience with building scalable applications, and ability to write clean, maintainable code in Node.js.
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1 - What is Node.js?
Node.js is an open source, cross platform runtime environment that allows developers to run JavaScript code outside of a web browser. It uses the V8 JavaScript engine from Google Chrome to execute code and is commonly used for building server side applications.
2) What is npm?
npm, which stands for Node Package Manager, is a package manager for Node.js and JavaScript. It consists of a command line client and an online database of public and paid for private packages. Developers use npm to install, share, and manage dependencies in their projects.
3) What is an event loop in Node.js?
The event loop in Node.js is a mechanism that allows asynchronous, non blocking operations to be handled efficiently. It enables Node.js to perform I/O operations without blocking the execution of other code. This results in better scalability and performance for applications that handle a large number of concurrent requests.
4) What is the role of callbacks in Node.js?
Callbacks are a fundamental concept in Node.js that allows asynchronous functions to notify the caller once they have completed their task. As Node.js is single threaded and asynchronous, callbacks ensure that the program continues to run smoothly without waiting for slow I/O operations to complete.
5) What are streams in Node.js?
Streams in Node.js are a mechanism for handling data flow efficiently. They allow reading and writing large amounts of data in chunks, which can help in minimizing memory consumption and improving performance. Streams can be readable, writable, or both, and are commonly used in network communication and file processing operations.
6) Explain the concept of middleware in Express.js.
Middleware functions in Express.js are functions that have access to the request and response objects and can modify them as well as terminate the request response cycle. Middleware plays a crucial role in handling tasks like logging, authentication, error handling, and more in an Express.js application.
7) What is the difference between Node.js and AJAX?
Node.js is a server side runtime environment for executing JavaScript code, while AJAX (Asynchronous JavaScript and XML) is a client side technique for making asynchronous HTTP requests without reloading the entire page. Node.js enables server side programming, whereas AJAX enhances the interactivity of web pages.
8) How does Node.js handle child processes?
Node.js provides a module called `child_process` that allows developers to spawn child processes from their applications. This module enables Node.js programs to execute external commands or scripts, communicate with them through standard input/output, and manage their execution asynchronously.
9) How can you handle errors in Node.js?
In Node.js, errors can be handled using try catch blocks for synchronous code and event listeners like `process.on('uncaughtException')` for asynchronous code. It is essential to handle errors carefully to prevent crashes and provide appropriate responses to users in production applications.
10) What is clustering in Node.js?
Clustering in Node.js is a technique that allows multiple Node.js processes to share the same port and distribute incoming client requests across them. By leveraging the cluster module, developers can take advantage of multi core systems and improve the performance and reliability of Node.js applications.
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