NodeJs Interview Questions Answer
February 8, 2023
Case Studies ,web
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Q1: What is Node.js?
Answer: As an asynchronous event-driven JavaScript runtime, Node.js is designed to build scalable network applications. In the following “hello world” example, many connections can be handled concurrently. Upon each connection, the callback is fired, but if there is no work to be done, Node.js will sleep.
const http = require('http');
const hostname = '127.0.0.1';
const port = 3000;
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/plain');
res.end('Hello World');
});
server.listen(port, hostname, () => {
console.log(`Server running at http://${hostname}:${port}/`);
});Ś
Q2: What Can Node.js Do??
Answer:
- Node.js can generate dynamic page content
- Node.js can create, open, read, write, delete, and close files on the server
- Node.js can collect form data
- Node.js can add, delete, and modify data in your database
Q3: What are the two types of API functions in Node.js?
Answer: The two types of API functions in Node.js are:
- Asynchronous, non-blocking functions
- Synchronous, blocking functions
Q4: What are the key features of Node.js?
Answer: The following are the main benefits of using Node.js
- Asynchronous event-driven IO helps concurrent request handling – All APIs of the Node.js library are asynchronous that is non-blocking. It essentially means a Node.js-based server never waits for an API to return data. The server moves to the next API after calling it and a notification mechanism of Events of Node.js helps the server to get a response from the previous API call.
- Very Fast – Being built on Google Chrome’s V8 JavaScript Engine, the Node.js library is very fast in code execution.
- Single-Threaded but highly Scalable – Node.js uses a single-threaded model with event looping. The event mechanism helps the server to respond in a non-blocking way and makes server highly scalable as opposed to traditional servers which create limited threads to handle requests. Node.js uses a single-threaded program and the same program can service a much larger number of requests than traditional servers like Apache HTTP Server.
- No Buffering – Node.js applications never buffer any data. These applications simply output the data in chunks.
- Node.js library uses JavaScript – This is another important aspect of Node.js from the developer’s point of view. The majority of developers are already well-versed in JavaScript. Hence, development in Node.js becomes easier for a developer who knows JavaScript.
- There is an Active and vibrant community for the Node.js framework – The active community always keeps the framework updated with the latest trends in web development.
Q5: What are the core modules of Node.js?
Answer:
- EventEmitter
- Stream
- FS
- Net
- Global Objects
Q6: What is V8?
Answer: The V8 library provides Node.js with a JavaScript engine (a program that converts Javascript code into lower-level or machine code that microprocessors can understand), which Node.js controls via the V8 C++ API. V8 is maintained by Google, for use in Chrome.
The Chrome V8 engine :
- The V8 engine is written in C++ and used in Chrome and Nodejs.
- It implements ECMAScript as specified in ECMA-262.
- The V8 engine can run standalone we can embed it with our own C++ program.
Q7: What is an error-first callback?
Answer: Error-first callbacks are used to pass errors and data. The first argument is always an error object that the programmer has to check if something went wrong. Additional arguments are used to pass data.fs.readFile(filePath, function(err, data) {
if (err) {
//handle the error
}
// use the data object
});
For more questions Answers, you can refer here https://github.com/webrndexperts/Node.js-Coding-Interview-Questions
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