Node.js projects with source code<\/a> from beginners to advanced level. Practicing the projects will help you prepare for the Node.js coding job interview.<\/p>\n\n\n\nQ21. In the file systems- fs module, how does the readFileSync differ from readFile?<\/h3>\n\n\n\n
Sample Answer: <\/strong>The \u2018readFileSync\u2019 <\/strong>method reads a file in a blocking way, meaning it stops other tasks from running until the file is fully read. On the other hand, \u2018readFile\u2019 <\/strong>reads the file in a non-blocking way, allowing other tasks to continue while the file is being read.<\/p>\n\n\n\nQ22. What measures can be taken against SQL Injection in a Node.js Application?<\/h3>\n\n\n\n
Sample Answer: <\/strong>To prevent SQL injection in a Node.js application, use parameterized queries or prepared statements. These techniques ensure that user input is treated as data, not executable SQL code, effectively blocking injection attacks.\u00a0<\/p>\n\n\n\nThe following code is used to prevent SQL injection:<\/p>\n\n\n\n
const mysql = require('mysql2');\nconst connection = mysql.createConnection({\n});\nhost: 'localhost',\nuser: 'root',\npassword: \",\ndatabase: 'test',\nconst username = 'user1';\nconst query = 'SELECT * FROM users WHERE username = ?';\nconnection.execute(query, [username], (err, results) => {\n});\nif (err) throw err;\nconsole.log(results);\n<\/code><\/pre>\n\n\n\nQ23. How can you implement rate limiting in a Node.js application?<\/h3>\n\n\n\n
Sample Answer: <\/strong>Rate limiting controls the number of requests a user can make to a server within a specific time, protecting applications from abuse like DDoS attacks and ensuring fair resource usage. In Node.js, it can be implemented using express-rate-limit. For scalable setups, integrating Redis allows distributed rate limiting across multiple instances, ensuring consistent enforcement.<\/p>\n\n\n\nThe following code can also be used to implement rate limiting:<\/p>\n\n\n\n
const express = require('express');\nconst rateLimit = require('express-rate-limit');\nconst app = express();\nconst limiter = rateLimit({\n});\nwindowMs: 15 * 60 * 1000, \/\/ 15 minutes\nmax: 100, \/\/ limit each IP to 100 requests per windowMs\napp.use(limiter);\napp.get('\/', (req, res) => res.send('Rate limited!'));\napp.listen(3000);\n<\/code><\/pre>\n\n\n\nQ24. How do we deal with file uploads in a Node.js application?<\/h3>\n\n\n\n
Sample Answer: <\/strong>In the Express framework, file uploads are managed using the Multer middleware, which handles file storage in specified folders while also capturing and processing file details. <\/p>\n\n\n\nThe following is the code file uploads in Nodes.js:<\/p>\n\n\n\n
const express = require('express');\nconst multer = require('multer');\nconst upload = multer({ dest: 'uploads\/' });\nconst app = express();\napp.post('\/upload', upload.single('file'), (req, res) => {\n});\nres.send('File uploaded successfully!');\napp.listen(3000);\n<\/code><\/pre>\n\n\n\nQ25. How do we perform caching in Node.js?<\/h3>\n\n\n\n
Sample Answer: <\/strong>Caching in Node.js involves storing frequently accessed data temporarily to reduce redundant processing and improve application performance. This can be done in memory or using external caching systems like Redis. The example below demonstrates simple in-memory caching using a JavaScript object.\u00a0<\/p>\n\n\n\nThe following code can be used to perform caching in Node.js:<\/p>\n\n\n\n
const express = require('express');\nconst cache = {};\nconst app = express();\napp.get('\/data', (req, res) => {\nconst key = 'uniqueKey';\nif (cache[key]) {\n}\nreturn res.send(cache[key]);\nconst data = { message: 'This is cached data' };\ncache[key] = data;\nres.send(data);\n});\napp.listen(3000);\n<\/code><\/pre>\n\n\n\nQ26. How can you enforce different levels of async execution in Node.js?<\/h3>\n\n\n\n
Sample Answer: <\/strong>In Node.js, different levels of asynchronous execution can be enforced using async\/await <\/strong>to handle sequential execution of promises. In the code, tasks are processed one by one using await to ensure each task is completed before moving to the next.\u00a0<\/p>\n\n\n\nThe following is the code to enforce async:<\/p>\n\n\n\n
const express = require('express');\nconst cache = {};\nasync function process Tasks() {\nconst task1 = await new Promise((resolve) => setTimeout(() => resolve('Task 1 completed\"), 1000));\nconsole.log(task1);\nconst task2 = await new Promise((resolve) => setTimeout(() => resolve('Task 2 completed'), 1000));\nconsole.log(task2);\nprocessTasks();\n<\/code><\/pre>\n\n\n\nQ27. How can you monitor and debug in Node.js applications?<\/h3>\n\n\n\n
Sample Answer: <\/strong>Tools like PM2 and Node.js debugging flags (-\u2013inspect) and monitoring applications with console.time() are helpful. Here is the code that can be used to monitor and debug in Node.js application:<\/p>\n\n\n\nconst http = require('http');\nconst server = http.createServer((req, res) => {\n});\nconsole.time('Request duration');\nres.end('Hello, Debugging!');\nconsole.timeEnd('Request duration');\nserver.listen(3000, () => console.log('Server running on port 3000'));\n<\/code><\/pre>\n\n\n\nQ28. How can you compose a WebSocket server using Node.js?<\/h3>\n\n\n\n
Sample Answer: <\/strong>A WebSocket server in Node.js can be created using the ws library. Start by initializing a server on a specific port and listening for client connections. Handle connection and message events to establish real-time communication, enabling the server to send and receive messages dynamically with connected clients.\u00a0<\/p>\n\n\n\nTo compose a WebSocket server, the code given below is used:<\/p>\n\n\n\n
const WebSocket = require('ws');\nconst server = new WebSocket.Server({ port: 8080 });\nserver.on('connection', (socket) => {\nconsole.log('Client connected');\nsocket.on('message', (message) => {\nconsole.log('Received: ${message}');\nsocket.send('Message received!');\n});\n});\n<\/code><\/pre>\n\n\n\n