Node.js Quiz PDF

node js QUESTION 1 What is Node.js primarily used for? A. Frontend Development B. Backend Development C. Database Management D. Game Development Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 2 Which language does Node.js use? A. Python B....

node js QUESTION 1 What is Node.js primarily used for? A. Frontend Development B. Backend Development C. Database Management D. Game Development Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 2 Which language does Node.js use? A. Python B. Java C. JavaScript D. Ruby Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 3 Node.js is based on which runtime environment? A. V8 B. Chakra C. SpiderMonkey D. Rhino Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 4 How does Node.js handle I/O operations? A. Synchronous B. Asynchronous C. Concurrent D. Serial Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 5 Which keyword is used to import modules in Node.js? A. import B. include C. require D. fetch Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 6 What does module.exports do? A. Exports functions to other modules B. Initializes the module C. Imports other modules D. Sets up a new module Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 7 Which module is used for creating an HTTP server? A. http B. server C. os D. express Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 8 What does NPM stand for? A. Node Program Management B. Node Package Manager C. Network Program Manager D. Node Processing Module Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 9 How do you install a package globally using NPM? A. npm install B. npm install -g C. npm add D. npm -global install Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 10 What file contains dependencies for a Node.js project? A. config.json B. npm.json C. package.json D. dependencies.json Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 11 Which function executes code after a specified delay? A. setTimeout B. setInterval C. setDelay D. asyncFunction Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 12 Which Node.js module provides utilities for working with asynchronous callbacks? A. fs B. async C. util D. callbacks Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 13 Node.js relies on which architecture to handle events? A. Procedural B. Synchronous C. Event-driven D. Multi-threaded Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 14 Which module is central to event handling in Node.js? A. fs B. events C. http D. emitter Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 15 What is Express.js primarily used for in Node.js? A. Frontend styling B. Data modeling C. Server-side framework D. Testing Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 16 What function is used to create a route in Express.js? A. expressRoute() B. route() C. app.route() D. app.get() Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 17 Which of the following is a best practice in Node.js? A. Blocking I/O operations B. Using synchronous functions C. Using asynchronous patterns D. Ignoring error handling Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 18 What type of logging is recommended for production? A. console.log B. Verbose logging C. Structured logging D. Debug logging Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 19 Which protocol does WebSocket use? A. HTTP B. HTTPS C. ws:// D. socket.io Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 20 What is the primary purpose of WebSocket? A. Database connections B. Real-time, two-way communication C. File transfer D. Video streaming Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 21 In Express.js, middleware functions can modify the: A. Request and response objects B. Database schema C. Network protocols D. HTML templates Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 22 What is the typical position of middleware in Express routes? A. Before the route handlers B. After the route handlers C. Middleware is independent of route handlers D. Middleware is only used with errors Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 23 Which method is used to read data in chunks in Node.js? A. read() B. pipe() C. chunk() D. stream() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 24 Which type of stream is used to read data? A. Writable B. Readable C. Duplex D. Transform Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 25 Which function is used to read a file synchronously in Node.js? A. fs.read() B. fs.readSync() C. fs.readFileSync() D. fs.syncRead() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 26 How do you write data to a file in an asynchronous way? A. fs.writeFileSync B. fs.appendFile C. fs.writeFile D. fs.writeAsync Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 27 What does a Promise represent? A. A synchronous function B. A completed task C. An eventual result of an asynchronous operation D. A user input Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 28 What does the await keyword do in an async function? A. Pauses execution until the Promise is resolved B. Rejects a Promise C. Schedules a callback D. Cancels an async function Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 29 What is the purpose of the Event Loop in Node.js? A. Manages synchronous code B. Handles asynchronous operations C. Loads modules D. Manages HTTP requests Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 30 The Event Loop executes which type of operations first? A. Network I/O B. Timers C. Microtasks D. File operations Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 31 Which of the following is a Node.js feature? A. Blocking I/O B. Single-threaded event loop C. Multi-threaded architecture D. Client-side scripting Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 32 What kind of applications is Node.js well-suited for? A. CPU-intensive applications B. I/O-bound applications C. GUI-based applications D. Desktop applications Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 33 Which built-in method is used to output logs to the console in Node.js? A. log() B. console() C. output() D. console.log() Correct Answer: D Section: (none) Explanation Explanation/Reference: Modules and Require (Extended) QUESTION 34 Which of the following is NOT a core module in Node.js? A. os B. http C. express D. path Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 35 How would you import a custom module located in the same directory? A. require('./module') B. require('module') C. import('module') D. module.exports('./module') Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 36 How do you export multiple functions from a Node.js module? A. Use exports object with named properties B. Use module.exports with named properties C. Use return statement D. Import both functions in a single file Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 37 Which command lists globally installed npm packages? A. npm list B. npm list -g C. npm -global list D. npm show global Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 38 What does the --save flag do when installing an npm package? A. Installs the package locally B. Saves the package as a devDependency C. Adds the package to the dependencies field in package.json D. Deletes the package from node_modules Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 39 How do you update npm itself to the latest version? A. npm update npm B. npm install npm -g C. npm upgrade D. npm self-update Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 40 What does the callback function in asynchronous functions prevent? A. Race conditions B. Deadlocks C. Blocking code execution D. High memory usage Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 41 Which of the following can handle asynchronous operations in Node.js? A. Events B. Promises C. async/await D. All of the above Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 42 What is a callback hell? A. A situation with nested callbacks, making code unreadable B. Errors that occur in callback functions C. A place in memory where callbacks are stored D. When a callback is executed multiple times Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 43 How do you listen to events in Node.js? A. By calling event.on() B. By calling event.listen() C. By using event.subscribe() D. By creating a new EventListener() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 44 Which method is used to emit an event in Node.js? A. emit() B. on() C. trigger() D. call() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 45 What is a key advantage of an event-driven model in Node.js? A. It handles synchronous code efficiently B. It improves memory management C. It scales well for handling multiple I/O requests D. It requires no error handling Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 46 What is the default port used by Express applications? A. 80 B. 443 C. 3000 D. 5000 Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 47 Which middleware is commonly used for parsing JSON in Express? A. body-parser B. json-parser C. cookie-parser D. express-parser Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 48 How do you handle errors globally in Express? A. Using error-handling middleware B. Catching errors in every route C. Using try-catch in each route D. By ignoring error codes Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 49 What is a recommended way to structure a Node.js project? A. Keep all code in one file B. Use modularized code with separate files for routes, models, etc. C. Combine frontend and backend code D. Write all functions globally Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 50 What should you avoid when working with sensitive data in Node.js? A. Using environment variables B. Hardcoding sensitive information C. Using third-party libraries D. Minifying code Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 51 Why is it recommended to use async/await in Node.js applications? A. It improves error handling and readability B. It makes code synchronous C. It blocks the Event Loop D. It executes code faster Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 52 Which library is commonly used for WebSocket communication in Node.js? A. http B. ws C. socket.io D. net Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 53 What method initiates a WebSocket connection? A. ws.start() B. ws.connect() C. new WebSocket() D. ws.open() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 54 What does WebSocket enable for real-time applications? A. File upload B. Bi-directional communication C. Asynchronous file read D. HTTP-based communication Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 55 What is the role of next() in Express middleware? A. Ends the request-response cycle B. Passes control to the next middleware C. Caches the response D. Initializes the app Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 56 In which order does Express execute middleware functions? A. Alphabetical order B. Reverse order of declaration C. Order of declaration D. Random order Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 57 How can you pipe data from a readable stream to a writable stream in Node.js? A. readable.pipe(writable) B. writable.pipe(readable) C. readable.write(writable) D. writable.read(readable) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 58 Which event is emitted when a readable stream ends? A. close B. end C. finish D. stop Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 59 Which method is used to check if a file exists in Node.js? A. fs.existsSync() B. fs.fileExists() C. fs.check() D. fs.accessSync() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 60 Which fs method is used to delete a file asynchronously? A. fs.delete() B. fs.remove() C. fs.unlink() D. fs.rm() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 61 What does the then() method of a Promise do? A. Chains asynchronous operations B. Returns a resolved Promise C. Handles synchronous code D. Throws an error Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 62 How do you handle errors in a Promise chain? A. By using a second argument in then() B. By using a.catch() method C. By ignoring them D. By using await Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 63 What kind of tasks does the Event Loop prioritize in Node.js? A. Network requests B. Timers C. Microtasks D. File I/O Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 64 What are the phases of the Event Loop? A. Timers, I/O callbacks, close callbacks, poll, check, and immediate B. Main phase and secondary phase C. Setup and teardown D. Input phase and output phase Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 65 Which of the following describes Node.js's single-threaded model? A. All code executes on a single thread, blocking I/O B. Node.js uses multiple threads for I/O and executes code in parallel C. Node.js uses a single thread but handles I/O asynchronously D. Node.js is only capable of executing one process at a time Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 66 Which of the following is true about Node.js? A. Node.js is only for web servers B. Node.js uses an event-driven, non-blocking I/O model C. Node.js only works on Linux systems D. Node.js is a framework Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 67 Which built-in Node.js module allows you to work with the operating system? A. fs B. os C. http D. path Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 68 Which module allows you to parse JSON files in Node.js? A. json-parser B. json C. fs D. path Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 69 How do you access the version of a Node.js module from within your code? A. module.version B. require('module').version C. module.info() D. node.getVersion() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 70 How can you use a Node.js module without installing it? A. By using require() and specifying a path to the module B. By downloading the module manually C. By specifying global keyword D. By creating a symbolic link Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 71 Which command is used to initialize a new Node.js project and generate a package.json file? A. npm create B. npm init C. npm start D. npm install Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 72 How would you uninstall a package globally using NPM? A. npm uninstall -g B. npm remove --global C. npm delete -g D. npm remove --global Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 73 Which command can you use to check for outdated npm packages? A. npm outdated B. npm check C. npm list --outdated D. npm update --outdated Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 74 Which function is used to schedule a one-time delay for executing code in Node.js? A. setTimeout() B. setInterval() C. setDelay() D. asyncWait() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 75 What happens if a callback function is not passed to an asynchronous function? A. The function will execute synchronously B. The callback is ignored and the function continues executing C. The function throws an error D. The program stops running Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 76 Which method in Node.js can handle multiple asynchronous operations concurrently? A. async.series() B. async.parallel() C. Promise.all() D. async.all() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 77 How do you define an event emitter in Node.js? A. new EventEmitter() B. events.createEmitter() C. Emitter.create() D. new EventListener() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 78 What will happen if an event is emitted but no listeners are attached in Node.js? A. Nothing happens B. The event will be lost C. Node.js throws an error D. Node.js will create a default listener Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 79 How do you remove a listener from an event emitter? A. emitter.removeListener(event, listener) B. emitter.off(event, listener) C. emitter.remove(event) D. emitter.remove(listener) Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 80 Which method is used to serve static files in Express.js? A. app.use(express.static()) B. express.serveStatic() C. app.serveStatic() D. express.static() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 81 Which HTTP method does Express.js use to handle POST requests? A. app.get() B. app.post() C. app.put() D. app.delete() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 82 Which of the following is correct for handling errors in Express? A. app.error() B. app.handleError() C. app.use() with a four-argument function D. express.use() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 83 What should be the main concern when handling errors in Node.js? A. Ignore errors for faster execution B. Propagate errors to higher-level handlers for logging and reporting C. Log errors without stopping execution D. Catch and suppress errors to prevent crashes Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 84 Which tool is commonly used for testing Node.js applications? A. Jest B. Mocha C. Jasmine D. All of the above Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 85 Why is using environment variables for configuration considered a best practice? A. It allows easier switching between development, staging, and production environments B. It helps to debug the application C. It improves code readability D. It keeps configuration details in the codebase Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 86 How do WebSockets maintain an open connection? A. By keeping an HTTP request open B. By using long polling C. By maintaining a persistent TCP connection D. By creating a new connection for each message Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 87 Which of the following best describes WebSocket's advantages? A. Full-duplex communication with low latency B. Single-direction communication only C. No support for large messages D. Slower than HTTP Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 88 Which WebSocket event is fired when the connection is closed? A. close B. end C. terminate D. disconnect Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 89 What is the purpose of body parsers in Express.js middleware? A. To parse incoming request bodies in various formats B. To handle errors in the request body C. To compress incoming requests D. To convert request bodies to JSON Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 90 Which method in Express allows for chaining multiple middleware? A. app.all() B. app.use() C. app.route() D. app.middleware() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 91 Which HTTP method is used to mount middleware that applies to a specific route? A. app.use() B. app.get() C. app.post() D. app.all() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 92 What is the difference between a readable and a writable stream in Node.js? A. Readable streams emit data that can be consumed, while writable streams accept data to write B. Readable streams store data, while writable streams send data C. Readable streams are for network operations, writable streams are for file I/O D. Writable streams process data asynchronously, readable streams process it synchronously Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 93 Which stream method is used to pipe the output of one stream into another? A. pipe() B. link() C. merge() D. flow() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 94 Which method allows asynchronous reading of a file in Node.js? A. fs.readFileSync() B. fs.readFile() C. fs.read() D. fs.asyncRead() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 95 Which of the following will create a new directory asynchronously? A. fs.mkdirSync() B. fs.createDirectory() C. fs.mkdir() D. fs.create() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 96 Which of the following does the async keyword indicate in front of a function? A. The function will return a Promise B. The function executes synchronously C. The function will handle asynchronous events D. The function is error-prone Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 97 What does Promise.all() return when one of the promises fails? A. Promise.reject() B. Promise.all() ignores the failure C. Promise.all() waits for all promises D. Promise.all() rejects with the error of the first failed promise Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 98 At which phase does the Event Loop process I/O events? A. Poll phase B. Timer phase C. Check phase D. Immediate phase Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 99 What is the main role of the Event Loop in Node.js? A. Handle HTTP requests B. Manage event listeners and asynchronous operations C. Execute synchronous code only D. Process database queries Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 100 Which phase comes after the poll phase in the Node.js Event Loop? A. Check phase B. Immediate phase C. Timer phase D. Idle phase Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 101 Which of the following can be considered an advantage of using Node.js for server-side development? A. High CPU usage B. Non-blocking I/O model C. Multi-threaded execution D. Supports synchronous file I/O Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 102 What does the process.exit() method do in a Node.js application? A. Exits the process without cleaning up resources B. Stops the event loop and terminates the Node.js process C. Exits the current function D. Pauses the application execution Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 103 Which of the following is used to handle child processes in Node.js? A. Os B. http C. child_process D. fs Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 104 What does the module.exports object in Node.js do? A. Exports data from one module to another B. Sets the default global object C. Imports data into the current module D. Imports libraries from other modules Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 105 Which of the following is NOT a feature of Node.js modules? A. Encapsulation of code B. Code reusability C. Blocking I/O D. Support for synchronous code execution Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 106 Which of the following will import a file located in a different directory? A. require('./myModule') B. require('../myModule') C. require('/myModule') D. import myModule Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 107 Which command installs all dependencies listed in package.json? A. npm install B. npm update C. npm upgrade D. npm start Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 108 Which file is created when you initialize a Node.js project using npm init? A. index.js B. node_modules.json C. package.json D. dependencies.json Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 109 How can you uninstall a package without removing its dependencies? A. npm remove --no-deps B. npm uninstall C. npm delete D. npm clear Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 110 Which of the following is a correct way to use async/await in Node.js? A. Using await inside non-async functions B. Using async in place of promises C. Wrapping the function call in a promise manually D. Using await only with synchronous functions Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 111 How do you execute multiple promises in parallel using Promise.all()? A. Promise.all([promise1, promise2]) B. Promise.all(promise1, promise2) C. Promise.all(promise1 && promise2) D. Promise.parallel([promise1, promise2]) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 112 Which is the best way to handle errors in async functions? A. Using.catch() after calling the async function B. Wrapping async calls inside try/catch blocks C. Letting the function crash if an error occurs D. Returning null or undefined for errors Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 113 In Node.js, what type of pattern is commonly used for managing events? A. Publisher-Subscriber pattern B. Observer pattern C. Event Queue pattern D. Request-Response pattern Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 114 What is emitted when an error occurs in Node.js Event Emitters? A. error event B. exception event C. errorOccurred event D. failure event Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 115 Which method allows you to remove all listeners for a specific event in Node.js? A. emitter.removeAllListeners() B. emitter.removeListeners() C. emitter.clearListeners() D. emitter.deleteListeners() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 116 What does app.listen() do in an Express.js application? A. Starts a web server that listens for incoming HTTP requests B. It listens for errors in the application C. Starts a database connection D. Mounts middleware on routes Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 117 How would you define a route for handling GET requests at the /home path in Express? A. app.get('/home', function(req, res) {...}) B. app.route('/home').get(function(req, res) {...}) C. app.router('/home').get(function(req, res) {...}) D. app.router('/home').post(function(req, res) {...}) Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 118 Which middleware is used to handle cookie parsing in Express? A. cookie-parser B. cookie-handler C. cookie-manager D. express-cookie Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 119 What is the purpose of using a.env file in Node.js projects? A. To manage environment variables B. To define constants C. To store file paths D. To store sensitive code Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 120 Which of the following is a best practice when dealing with untrusted data in Node.js applications? A. Always sanitize input to prevent security vulnerabilities B. Ignore potential security threats from untrusted data C. Store sensitive data like passwords in plain text D. Validate data only on the client side Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 121 Which logging library is often used in Node.js applications for structured logging? A. Winston B. log4js C. morgan D. All of the above Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 122 Which event is triggered when a WebSocket connection is established? A. Open B. Connect C. Start D. Ready Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 123 How do you send data from a WebSocket server to the client? A. ws.send(data) B. ws.emit(data) C. ws.push(data) D. ws.broadcast(data) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 124 What is the purpose of WebSocket's ping and pong messages? A. To maintain the connection alive and measure latency B. To send binary data C. To exchange authentication tokens D. To compress the message payload Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 125 What does the next() function do in middleware for handling requests in Express.js? A. It proceeds to the next middleware or route handler B. It closes the connection to the client C. It terminates the request-response cycle D. It suspends the request Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 126 Which type of middleware is executed before route handling middleware in Express? A. Application-level middleware B. Route-level middleware C. Error-handling middleware D. Built-in middleware Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 127 How can you limit the number of requests made by the client in a certain period? A. By using rate-limiting middleware B. By applying custom logic to each route C. By using app.use() for validation D. By setting cookies in the response Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 128 Which method is used to read data from a readable stream? A. stream.read() B. stream.pipe() C. stream.output() D. stream.get() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 129 What is the advantage of using streams over loading a file entirely into memory? A. Streams allow reading and writing data as it is being processed, reducing memory usage B. Streams store data in memory and thus are faster C. Streams process files more slowly D. Streams require less CPU usage Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 130 How can you pause a readable stream? A. stream.pause() B. stream.stop() C. stream.close() D. stream.suspend() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 131 Which of the following is the primary reason Node.js is preferred for I/O-heavy applications? A. It uses a synchronous execution model B. It uses non-blocking, event-driven architecture C. It is easy to implement multi-threading D. It runs on multiple processors concurrently Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 132 Which of the following is true about Node.js? A. Node.js is used for frontend development only B. Node.js is a multi-threaded framework C. Node.js is a runtime environment that runs JavaScript code outside of the browser D. Node.js is used only for building web pages Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 133 Which built-in Node.js module helps you work with paths and file system operations? A. http B. path C. events D. fs Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 134 How would you require a JSON file in Node.js? A. require('./data.json') B. import('./data.json') C. require('./data.json') (but only if it contains JavaScript code) D. require('./data') Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 135 Which command can you use to create a custom module in Node.js? A. node module.create B. require('./myModule') C. module.exports D. Custom modules are not allowed in Node.js Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 136 What is the purpose of exports in Node.js? A. It is used to define global variables B. It is used to import external libraries C. It is used to export functions or objects from a module D. It initializes Node.js built-in modules Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 137 Which command installs a package globally? A. npm install B. npm install -g C. npm add D. npm global-install Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 138 How can you search for a package using NPM? A. npm search B. npm find C. npm search --global D. npm query Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 139 What is package-lock.json used for? A. To lock the current version of Node.js B. To lock the versions of dependencies for consistency C. To specify the package manager version D. To store the list of globally installed packages Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 140 What happens when you call an asynchronous function without a callback in Node.js? A. The function execution is blocked until completion B. An error is thrown C. The callback is passed automatically D. The function executes synchronously Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 141 What is the main difference between callbacks and promises in Node.js? A. Promises are synchronous, while callbacks are asynchronous B. Promises simplify chaining of asynchronous operations, while callbacks can lead to callback hell C. Callbacks allow more fine-grained control over I/O operations D. Promises are only useful for I/O operations, callbacks are for CPU-intensive tasks Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 142 Which of the following would you use to handle multiple asynchronous tasks and wait for them all to complete? A. Promise.any() B. Promise.all() C. async.parallel() D. Promise.resolve() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 143 What is the default maximum number of listeners for each event in Node.js's EventEmitter? A. 10 B. 100 C. 50 D. 1 Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 144 Which of the following is true about events in Node.js? A. Events are used only for managing HTTP requests B. Events provide an easy way to handle asynchronous operations without blocking C. Node.js does not support event-driven programming D. Events are only used for file system operations Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 145 How do you emit a custom event in Node.js? A. emitter.emit('eventName') B. emitter.raise('eventName') C. emitter.dispatch('eventName') D. emitter.trigger('eventName') Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 146 What does the express.Router() method do? A. Creates a new middleware function B. Creates a route handler for a specific path C. Creates a new router object for routing HTTP requests D. Sets a custom error handler Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 147 Which of the following is true about using middleware in Express.js? A. Middleware runs before the route handler B. Middleware runs after the route handler C. Middleware can only handle POST requests D. Middleware can only be used with static files Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 148 Which HTTP method should you use to handle form submissions in Express? A. app.get( B. app.delete() C. app.post() D. app.head() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 149 Which of the following should you consider when writing scalable applications in Node.js? A. Using blocking I/O calls B. Avoiding error handling C. Leveraging asynchronous code D. Writing all logic in a single function Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 150 Which of the following is a good practice when deploying a Node.js application in production? A. Enabling full error logs in production B. Running Node.js as a non-root user C. Disabling clustering D. Ignoring security updates Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 151 What is one of the most common ways to monitor a Node.js application in production? A. Using console.log() for every request B. Using application performance monitoring (APM) tools like New Relic or Datadog C. Only running the application locally D. Disabling error reporting in production Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 152 What type of protocol does WebSocket use for communication? A. HTTP B. HTTPS C. TCP D. UDP Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 153 What happens if you try to send a message over a closed WebSocket connection? A. The message is queued B. The message is lost C. An error is thrown D. The message is automatically retransmitted Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 154 Which of the following is a key feature of WebSocket? A. One-way communication from client to server B. Persistent, full-duplex communication between the client and server C. Only supports binary data D. Uses request-response model like HTTP Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 155 How can you create a custom error-handling middleware in Express.js? A. By using app.use() with four arguments B. By using app.error() C. By using app.custom() D. By defining an error event listener Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 156 Which middleware in Express helps in parsing incoming JSON data? A. express.json() B. express.bodyParser() C. express.parseJSON() D. express.body() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 157 How would you prevent a specific route in Express from being accessed by unauthorized users? A. Using middleware for authentication and authorization checks B. Redirecting users to the homepage C. Disabling routing for that path D. Allowing all routes to handle authentication Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 158 Which of the following methods can be used to pipe a readable stream to a writable stream? A. stream.pipe(destination) B. stream.writeTo(destination) C. stream.transfer(destination) D. stream.send(destination) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 159 What type of stream is used for reading data from a file in Node.js? A. Readable stream B. Writable stream C. Duplex stream D. Transform stream Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 160 What method would you use to end a writable stream after writing data? A. stream.close() B. stream.end() C. stream.stop() D. stream.closeWrite() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 161 Which Node.js function is used to get the current working directory? A. process.cwd() B. os.cwd() C. path.cwd() D. process.getcwd() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 162 What is the primary role of Node.js in the MEAN stack? A. It provides the database interface B. It is used for backend server-side logic C. It is used for client-side rendering D. It handles the routing of HTTP requests Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 163 Which of the following is NOT a common use case for Node.js? A. Real-time web applications B. APIs for single-page applications C. Heavy computational tasks D. Microservices Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 164 How would you load a local module in Node.js? A. require('moduleName') B. require('./moduleName') C. import('./moduleName') D. module.import('./moduleName') Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 165 Which of the following is the correct way to export a single function from a module in Node.js? A. module.exports = function() {... }; B. exports = function() {... }; C. module.export = function() {... }; D. export function() {... }; Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 166 Which Node.js module can be used to interact with the operating system and retrieve system information? A. Path B. Os C. http D. fs Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 167 How would you view the details of a specific package installed via NPM? A. npm show B. npm info C. npm details D. Both a and b Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 168 Which of the following NPM commands creates a package-lock.json file? A. npm install B. npm init C. npm update D. npm config set Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 169 What command is used to install a package as a development dependency in NPM? A. npm install --dev B. npm install --save-dev C. npm dev-install D. npm install -d Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 170 Which function is used to handle the result of an asynchronous operation in a promise chain? A..catch() B..then() C..finally() D..complete() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 171 What does the async keyword do in an asynchronous function? A. It allows the function to be executed synchronously B. It signals the function to return a promise C. It automatically catches all errors in the function D. It delays the execution of the function Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 172 What happens if you throw an error inside an async function? A. It is caught automatically by the catch() method B. It is thrown immediately C. It creates a promise rejection D. It logs the error to the console Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 173 Which of the following is true about event-driven architecture in Node.js? A. It relies on synchronous execution of events B. It uses callbacks and event emitters to handle multiple operations concurrently C. It is used only for web servers D. It does not support asynchronous programming Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 174 How can you modify the maximum number of listeners for an event in Node.js? A. emitter.setMaxListeners(20) B. emitter.maxListeners(20) C. emitter.changeMaxListeners(20) D. emitter.setListeners(20) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 175 Which method would you use to listen for custom events in Node.js? A. emitter.on('eventName', callback) B. emitter.addListener('eventName', callback) C. Both a and b D. emitter.listen('eventName', callback) Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 176 Which middleware function is commonly used to log HTTP requests in Express.js? A. Morgan B. body-parser C. cookie-parser D. express-log Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 177 How would you add a route that listens for PUT requests at the /update path in Express? A. app.put('/update', (req, res) => {...}) B. app.patch('/update', (req, res) => {...}) C. app.put('/update', (req) => {...}) D. app.post('/update', (req, res) => {...}) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 178 Which of the following is the correct way to handle static files in Express? A. app.use(express.static('public')) B. app.static('public') C. app.useStatic('public') D. app.staticFiles('public') Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 179 Which of the following is a best practice for handling errors in Node.js applications? A. Throwing errors without logging them B. Using try/catch for synchronous code and.catch() for promises C. Letting errors propagate to the top level D. Ignoring errors to prevent performance issues Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 180 Which of the following is the best approach for managing a large Node.js application? A. Writing all the code in a single file B. Using modules to break down the application into smaller components C. Only using a single routing file for simplicity D. Avoiding the use of external libraries Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 181 What should you do to handle uncaught exceptions in a Node.js application? A. Let the process exit and restart it manually B. Use process.on('uncaughtException', callback) to handle them C. Ignore the error, Node.js will automatically handle it D. Exit the process and do not restart it Correct Answer: B Section: (none) Explanation Explanation/Reference: WebSocket Communication (Extended) QUESTION 182 Which WebSocket method would you use to send a message from the server to the client? A. ws.send() B. ws.emit() C. ws.sendMessage() D. ws.push( Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 183 Which of the following is the correct way to close a WebSocket connection from the server? A. ws.close() B. ws.disconnect() C. ws.terminate() D. ws.end() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 184 How do you handle WebSocket message events in the client? A. socket.on('message', (data) => {...}) B. socket.receive('message', (data) => {...}) C. socket.message('message', (data) => {...}) D. socket.listen('message', (data) => {...}) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 185 How would you add a middleware that runs only for specific HTTP methods in Express? A. app.use(method, middleware) B. app.use('/path', method, middleware) C. app[method]('/path', middleware) D. app.method('/path', middleware) Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 186 Which of the following is used to serve static files in Express? A. app.use(express.static(path)) B. app.serve(path) C. app.staticFiles(path) D. app.serveStatic(path) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 187 How would you add a middleware for handling JSON payloads in Express.js? A. app.use(express.json()) B. app.json(express()) C. app.bodyParser() D. app.use(express.payload()) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 188 Which of the following streams can be used to transform data before passing it to the next stream? A. Readable stream B. Writable stream C. Transform stream D. Duplex stream Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 189 Which method is used to pause a writable stream? A. stream.pause() B. stream.stop() C. stream.end() D. stream.suspend() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 190 What is the purpose of the stream.finished() method in Node.js? A. To check if the stream is currently active B. To check if the stream has completed processing C. To stop all ongoing operations D. To close the stream immediately Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 191 What is the output of console.log(process.argv) in a Node.js program? A. Array of command-line arguments passed to the program B. Path of the current script C. The Node.js version D. List of dependencies in package.json Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 192 Which of the following would be the best way to ensure your Node.js application handles a large number of concurrent users? A. Use synchronous I/O operations B. Use asynchronous I/O operations with callbacks or promises C. Run Node.js in a single-threaded environment D. Ignore error handling to improve performance Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 193 Which command would you use to check the version of Node.js installed on your system? A. node –version B. node –v C. node version D. Both a and b Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 194 What does require() do in Node.js? A. Loads a file and evaluates it, returning the exported module B. Loads a library into the global namespace C. Executes the entire Node.js program D. Imports a module from another server Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 195 How do you export an object from a Node.js module? A. module.export = object B. exports = object C. module.exports = object D. object.export() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 196 Which of the following will correctly import the fs module in Node.js? A. import fs from 'fs' B. require('fs') C. import * as fs from 'fs' D. import module from 'fs' Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 197 What does the command npm uninstall do? A. Removes the package and its dependencies from the project B. Removes the package from the global package registry C. Removes the package only from the node_modules directory D. Uninstalls the global NPM package Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 198 What does the npm outdated command do? A. Lists all outdated packages that need updating B. Displays the status of the current project C. Lists all installed global packages D. Updates packages to the latest version Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 199 What is the purpose of the npm update command? A. It updates the project's dependencies to the latest versions specified in package.json B. It updates Node.js itself C. It upgrades NPM to the latest version D. It only updates the dependencies in package-lock.json Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 200 Which of the following is a method used to handle multiple promises concurrently and return a single promise? A. Promise.all() B. Promise.race() C. Promise.finally() D. Promise.any() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 201 What does await do in JavaScript? A. It pauses the execution of the async function until the promise is resolved or rejected B. It starts a promise-based function C. It handles promise rejections D. It waits for a setTimeout to finish Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 202 Which function is used to handle promise rejections in Node.js? A..catch() B..then() C..finally() D..reject() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 203 What is an event loop in Node.js? A. A mechanism that schedules and processes events asynchronously in a non-blocking way B. A loop that listens to events in real-time C. A function that processes events sequentially D. A framework for handling multiple clients Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 204 How can you remove all listeners for a specific event from an EventEmitter instance? A. emitter.removeListener('eventName') B. emitter.removeAllListeners('eventName') C. emitter.off('eventName') D. emitter.clearListeners('eventName') Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 205 What is the purpose of the once() method in Node.js EventEmitter? A. To listen for events that should be triggered only once B. To fire an event only once during program execution C. To reset all events to be triggered once D. To delay an event execution until a condition is met Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 206 Which method is used to send an HTTP response with a specific HTTP status code in Express? A. res.statusCode(404) B. res.sendStatus(404) C. res.send(404) D. res.status(404).send('Not Found') Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 207 Which of the following is used to parse incoming requests with JSON payloads in Express? A. app.use(express.json()) B. app.use(bodyParser.json()) C. app.use(express.bodyParser()) D. app.bodyParser() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 208 How can you chain route handlers in Express.js? A. Using app.route() B. Using app.all() C. Using app.handle() D. Using app.middleware() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 209 Which of the following is a common practice for optimizing performance in Node.js? A. Avoid using asynchronous code B. Use global variables extensively to speed up access C. Avoid using console.log() in production D. Ignore error handling to avoid overhead Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 210 When should you use environment variables in a Node.js application? A. To store sensitive configuration data like API keys and database credentials B. To store application logic C. To store client-side data for use in templates D. Only to store temporary data Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 211 What is the recommended way to handle long-running operations in a Node.js application? A. Perform them synchronously to ensure they are completed before continuing B. Use child processes or worker threads for CPU-intensive operations C. Store them in the database and process them later D. Always run them inside an event listener Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 212 Which event is triggered when the WebSocket connection is closed? A. ws.disconnect B. ws.close C. ws.end D. ws.onclose Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 213 How can you broadcast a message to all connected WebSocket clients from the server? A. Send the message to each client individually using ws.send() B. Use ws.broadcast() C. Use ws.sendToAll() D. Node.js does not support broadcasting natively Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 214 Which protocol is WebSocket built upon? A. HTTP B. HTTPS C. TCP D. UDP Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 215 Which of the following is the purpose of express.static() middleware? A. To handle static file serving B. To parse incoming JSON payloads C. To manage authentication D. To log HTTP requests Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 216 How would you use middleware to handle errors in Express.js? A. app.use(errorHandler) B. app.all('/error', errorHandler) C. app.error(errorHandler) D. app.use('/error', errorHandler) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 217 What is the purpose of the next parameter in Express middleware? A. It is used to pass control to the next middleware function in the stack B. It is used to delay the execution of middleware C. It stores a reference to the next middleware function D. It signals the end of a middleware chain Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 218 Which of the following is used to run a Node.js application? A. node B. node run C. node execute D. node start Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 219 What is the default port number for a Node.js server? A. 3000 B. 8080 C. 80 D. 5000 Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 220 Which method is used to listen for incoming requests on a specific port in Node.js? A. server.listen(port) B. server.start(port) C. server.open(port) D. server.bind(port) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 221 What happens if a module is required multiple times in Node.js? A. It is loaded and executed again each time B. It is cached after the first require and does not execute again C. It throws an error D. It is treated as a new module each time Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 222 Which of the following is true about CommonJS modules in Node.js? A. They use the import statement for importing modules B. They use require() for importing modules C. They only support synchronous loading D. They do not support module exports Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 223 How would you export multiple functions or variables from a Node.js module? A. module.exports = [function1, function2] B. module.exports = { function1, function2 } C. exports = { function1, function2 } D. module.exportMultiple = { function1, function2 } Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 224 How would you install a package globally using npm? A. npm global install B. npm install --global C. npm add -g D. npm global Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 225 What does the npm audit command do? A. Scans your dependencies for security vulnerabilities B. Displays the outdated packages in your project C. Installs missing dependencies D. Provides an overview of the project's structure Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 226 What command is used to create a package.json file for a Node.js project? A. npm create B. npm init C. npm setup D. npm package Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 227 Which of the following is true about setTimeout() in Node.js? A. It immediately executes the function synchronously B. It executes the function asynchronously after a specified delay C. It executes the function only once per event loop D. It blocks the event loop until the delay has passed Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 228 What does Promise.all() return when all promises are resolved successfully? A. An array of the resolved values B. A single resolved value C. A resolved promise containing the first resolved value D. A rejected promise Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 229 What does the finally() method do in a promise chain? A. It catches any errors in the promise chain B. It executes after the promise is settled (resolved or rejected) C. It prevents further promise chaining D. It cancels the promise execution Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 230 Which of the following is the best description of an event-driven architecture in Node.js? A. A system where events (such as button clicks) trigger specific actions B. A system where everything runs in a sequential, blocking order C. A system where each action is triggered by time-based intervals D. A system where events are polled in a loop for each iteration Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 231 How can you emit a custom event in Node.js using an EventEmitter? A. emitter.emit('eventName', data) B. emitter.trigger('eventName', data) C. emitter.raise('eventName', data) D. emitter.dispatch('eventName', data) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 232 What is the purpose of the process.on('uncaughtException', callback) method? A. It listens for and handles uncaught exceptions in the Node.js application B. It processes all exceptions and prevents them from terminating the application C. It generates uncaught exceptions deliberately for testing D. It logs uncaught exceptions to the console Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 233 Which of the following is used to handle 404 errors in Express.js? A. app.use((req, res, next) => { res.status(404).send('Not Found'); }); B. app.error(404, (req, res) => {... }); C. app.useError(404, handler) D. app.handle(404, (req, res) => {... }); Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 234 What is the purpose of the app.all() method in Express? A. It is used to define a handler for all HTTP methods (GET, POST, etc.) for a given path B. It is used to serve all types of files from a specific directory C. It defines all routes globally for the app D. It is used to listen for incoming requests on all ports Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 235 How would you use Express to parse a URL-encoded body (as submitted by a form)? A. app.use(express.urlencoded({ extended: true })) B. app.use(bodyParser.urlencoded({ extended: true })) C. app.use(express.bodyParser({ extended: true })) D. app.urlencoded() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 236 Which of the following best practices should be followed when deploying a Node.js application in production? A. Using synchronous file reads to improve performance B. Enabling console.log() for debugging C. Using environment variables to store sensitive information D. Ignoring unhandled promise rejections Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 237 What is the recommended method for error handling in an asynchronous function in Node.js? A. Ignoring the errors for better performance B. Using a try/catch block inside an async function C. Writing custom error handling functions for every operation D. Using the error event in Node.js Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 238 What is the advantage of using worker threads in Node.js? A. They allow for concurrent I/O operations in a single thread B. They allow Node.js to execute CPU-intensive operations without blocking the event loop C. They speed up event-driven asynchronous programming D. They reduce memory usage by executing in the background Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 239 Which of the following would you use to send a message to all clients connected to the WebSocket server? A. ws.broadcast('message') B. ws.sendToAll('message') C. You would need to manually iterate over each connected WebSocket instance and send the message D. ws.emit('message') Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 240 Which event is fired when a message is received from the client in a WebSocket connection? A. Message B. Data C. Receive D. onmessage Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 241 How do you handle a WebSocket error in the client? A. socket.on('error', callback) B. socket.error(callback) C. socket.onerror(callback) D. socket.catch(callback) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 242 Which of the following middleware functions is used to parse cookies in an Express.js app? A. cookieParser() B. express.cookie() C. cookieParserMiddleware() D. app.cookies() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 243 What is the default status code returned by Express when no status code is specified? A. 200 (OK) B. 404 (Not Found) C. 500 (Internal Server Error) D. 301 (Moved Permanently) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 244 Which of the following is used to prevent Cross-Origin Resource Sharing (CORS) issues in Express.js? A. express-cors B. cors middleware C. app.enableCORS() D. app.allowCrossOrigin() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 245 Which of the following is a core module of Node.js? A. Fs B. Path C. http D. All of the above Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 246 Which command is used to run a Node.js file directly from the terminal? A. node run B. node start C. node D. node execute Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 247 In Node.js, which method can you use to read a file asynchronously? A. fs.readFileSync() B. fs.readFile() C. fs.read() D. fs.loadFile() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 248 How would you require a built-in Node.js module in your project? A. import fs from 'fs' B. require('fs') C. import * as fs from 'fs' D. load('fs') Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 249 Which method would you use to dynamically load a module in Node.js? A. require() B. import() C. load() D. module.import() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 250 What does module.exports do in a Node.js module? A. Exports the module’s public API B. Import the module’s public API C. Imports functions from other modules D. Defines the entire module inside a file Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 251 What does the command npm run do? A. Executes a script defined in the package.json file B. Installs a new package C. Compiles JavaScript code D. Runs the app in production mode Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 252 What does the npm install command do when run in an existing project? A. Installs all dependencies listed in the package.json file B. Updates the package.json file C. Removes the node_modules directory D. Installs a new dependency into the project Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 253 What is the purpose of the npm start command in a Node.js project? A. It starts the server defined in the scripts section of package.json B. It installs all project dependencies C. It initializes a new Node.js application D. It starts the app in debug mode Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 254 What does the setImmediate() function do in Node.js? A. Executes a callback function after the current event loop completes B. Executes a callback function after a specified delay C. Executes a callback function asynchronously after a specified interval D. Executes a callback function synchronously before the next event loop Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 255 What is the result of calling Promise.reject('error')? A. It creates a resolved promise with the value 'error' B. It immediately rejects the promise with the error message 'error' C. It throws an error in the synchronous code D. It creates a pending promise Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 256 What is a key difference between setTimeout() and setImmediate()? A. setTimeout() executes a callback after the specified delay, while setImmediate() runs the callback on the next iteration of the event loop B. setTimeout() always runs synchronously, while setImmediate() is asynchronous C. setTimeout() is used to handle errors, while setImmediate() handles regular tasks D. setTimeout() executes in the next event loop, while setImmediate() waits until the script is finished Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 257 Which of the following is true about the EventEmitter class in Node.js? A. It is used to handle HTTP requests in Node.js B. It is used to manage file system operations C. It allows an object to emit named events that listeners can respond to D. It only supports one listener per event Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 258 Which of the following is the correct syntax to add an event listener to an EventEmitter instance? A. emitter.addListener('event', callback) B. emitter.on('event', callback) C. emitter.subscribe('event', callback) D. emitter.event(callback) Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 259 What does the process.nextTick() function do in Node.js? A. Executes a callback after the current operation completes, before the event loop continues B. Executes a callback after the current event loop iteration C. Schedules a task to be performed immediately D. Immediately terminates the process and logs errors Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 260 Which of the following is the correct way to define a GET route in Express? A. app.route('/path').get((req, res) => {... }) B. app.get('/path', (req, res) => {... }) C. app.define('/path').get((req, res) => {... }) D. app.post('/path').get((req, res) => {... }) Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 261 Which middleware function would you use to parse incoming form data in Express? A. express.bodyParser() B. express.json() C. express.urlencoded() D. bodyParser() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 262 What is the primary purpose of the next() function in Express middleware? A. To terminate the request-response cycle B. To send a response to the client C. To pass control to the next middleware function D. To execute the current middleware again Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 263 Which of the following is a best practice for handling errors in Node.js applications? A. Always log errors to the console and allow the application to continue running B. Return detailed error messages to the client to help debug C. Use try/catch blocks and reject unhandled promise rejections D. Let errors go unhandled to improve performance Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 264 What is the best way to scale a Node.js application? A. Run the application on multiple threads in a single process B. Use multiple instances of Node.js behind a load balancer C. Use a single thread for handling multiple requests D. Increase the number of synchronous I/O operations Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 265 What is the purpose of using dotenv in a Node.js application? A. It helps to parse cookies from incoming HTTP requests B. It allows you to manage environment variables easily in a.env file C. It is used to run Node.js applications in production mode D. It is a tool for managing API requests and responses Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 266 Which of the following is true about WebSocket communication in Node.js? A. WebSockets require HTTP/2 for communication B. WebSocket is a one-way communication protocol C. WebSockets provide full-duplex communication between client and server D. WebSockets can only be used with static websites Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 267 How would you close a WebSocket connection from the server side? A. ws.close() B. ws.disconnect() C. ws.terminate() D. ws.end() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 268 How can you handle errors when using WebSocket in a Node.js client? A. socket.onerror = function(event) {... } B. socket.onError(function(event) {... }) C. socket.catchError(function(event) {... }) D. socket.handleError(function(event) {... }) Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 269 Which of the following middleware functions would you use to serve static files in an Express.js application? A. app.static() B. express.static() C. app.serveStatic() D. serve.static() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 270 What is the primary function of middleware in an Express.js application? A. To execute HTTP requests synchronously B. To handle routing for each HTTP method C. To process requests, modify responses, and pass control to the next middleware D. To handle error handling and responses Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 271 Which middleware function is used to parse incoming JSON payloads in Express? A. express.json() B. express.bodyParser() C. express.parseJson() D. jsonParser() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 272 What does process.env in Node.js represent? A. The current file directory B. An object containing environment variables C. The version of Node.js D. A list of installed modules Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 273 How does Node.js handle multiple requests? A. Using multithreading B. Using a single-threaded, non-blocking I/O model C. By creating multiple instances of the app D. Using synchronous functions only Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 274 What is the purpose of exports in Node.js? A. To import modules B. To export objects and functions from a module C. To read external files D. To handle events Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 275 How do you make only specific functions or variables accessible from a Node.js module? A. Use exports.specificFunction = function() {... } B. Use export default specificFunction C. Use require.specificFunction D. Place the function at the top of the file Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 276 Which of the following statements is false regarding module.exports and exports? A. Both module.exports and exports are references to the same object initially B. You can reassign exports directly to export an object C. exports is a shorthand for module.exports D. Using module.exports allows exporting a single function or object Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 277 What file is used by npm to determine the dependencies of a project? A. package.json B. npm-config.json C. dependencies.json D. module.json Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 278 What command updates all packages to their latest versions in an npm project? A. npm update B. npm upgrade C. npm latest D. npm all-update Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 279 What does the ^ symbol in package.json version numbers represent? A. Updates to any version above the current B. Updates to the latest major version C. Updates to compatible minor versions D. Updates to only the latest patch version Correct Answer: C Section: (none) Explanation Explanation/Reference: Asynchronous Programming (Extended) QUESTION 280 Which of the following functions does not return a promise? A. setTimeout() B. fetch() C. fs.promises.readFile() D. Promise.resolve() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 281 How do you convert a callback-based function into a promise-based function in Node.js? A. Using async/await B. Using Promise.wrap() C. Using Promise.promisify() D. Using Promise.create() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 282 What will Promise.race([p1, p2, p3]) return if p2 resolves first? A. It returns the value from p2 B. It returns the values from all resolved promises C. It waits for all promises to settle D. It waits for the longest promise to resolve Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 283 Which method is used to remove a specific listener from an event in EventEmitter? A. emitter.removeListener(event, listener) B. emitter.off(event, listener) C. emitter.removeEvent(event) D. emitter(event, listener) Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 284 What event is emitted when an error occurs in Node.js? A. Error B. Exception C. Crash D. uncaughtException Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 285 How can you prevent an application from crashing when an unhandled error occurs in an EventEmitter? A. Listen to the error event on the emitter B. Use try/catch in synchronous functions C. Wrap the EventEmitter in a promise D. Ignore all errors in the application Correct Answer: A Section: (none) Explanation Explanation/Reference: Express.js Framework (Extended) QUESTION 286 How would you configure Express to serve static files from a directory? A. app.use(express.static('public')) B. app.static('public') C. app.serve('public') D. app.serveStatic('public') Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 287 What is the role of the app.listen() function in an Express application? A. It defines the application’s routes B. It binds the application to a network port for incoming connections C. It starts the application in debug mode D. It logs server requests Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 288 Which of the following methods defines middleware for handling JSON payloads in Express? A. app.use(express.json()) B. app.use(express.bodyParser()) C. app.json() D. app.bodyParser() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 289 What is the recommended way to secure environment variables in a Node.js project? A. Storing them directly in the code B. Using.env files and keeping them out of version control C. Hard-coding them in package.json D. Sharing them openly for all developers Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 290 What is a common way to improve application performance in Node.js? A. Using synchronous file operations B. Using asynchronous non-blocking methods C. Blocking the event loop for heavy tasks D. Using multiple single-threaded processes Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 291 Which tool is commonly used for logging in production-grade Node.js applications? A. console.log() B. fs.appendFile() C. Winston D. logger.debug() Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 292 Which protocol upgrade does WebSocket use to establish a connection over HTTP? A. HTTP/2 B. WebSocket handshake C. TCP/IP upgrade D. HTTP upgrade Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 293 Which event listener would you use to detect when a WebSocket connection is closed? A. socket.on('disconnect') B. socket.on('close') C. socket.on('end') D. socket.on('exit') Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 294 What is the purpose of ws.send() in a WebSocket server? A. To send a message to a specific client B. To send a message to all connected clients C. To broadcast to all clients and servers D. To close the connection Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 295 In Express, which method is typically used to handle errors across the application? A. app.error() B. app.use((err, req, res, next) => {... }) C. app.catch((err) => {... }) D. app.handleError((err) => {... }) Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 296 What is the order of middleware execution in Express.js? A. Alphabetical order B. In the order they are defined in the code C. Based on middleware priority level D. Random order Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 297 Which type of middleware can modify the request object in Express.js before it reaches the route handler? A. Error-handling middleware B. Application-level middleware C. Request-modifying middleware D. Route handler middleware Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 298 Which of the following is an example of a readable stream in Node.js? A. fs.createReadStream() B. fs.writeFile() C. fs.appendFile() D. http.get() Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 299 Which event is emitted by writable streams when they are ready to accept more data? A. Data B. Drain C. Ready D. open Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 300 What is the purpose of a for...of loop in JavaScript? A. Iterates over each property of an object B. Iterates over each character in a string C. Iterates over iterable objects like arrays, strings, and sets D. Iterates in reverse order Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 301 What is the output of the following code? javascript const arr = [1, 2, 3]; for (let i = 0; i < arr.length; i++) { if (i === 1) break; console.log(arr[i]); } A. 1, 2, 3 B. 2 C. 1 D. 1, 2 Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 302 Which loop would you use when the number of iterations is unknown but depends on a condition? A. for loop B. while loop C. do...while loop D. none of the above Correct Answer: AB Section: (none) Explanation Explanation/Reference: QUESTION 303 What is the main difference between for...in and for...of loops? A. for...in loops through array elements, and for...of loops through object properties B. for...in loops through object properties, and for...of loops through iterable elements C. Both loops function identically D. for...in is used only for arrays Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 304 How many times will the following loop execute? javascript let count = 0; while (count < 5) { count++; } A. 0 B. 4 C. 5 D. Infinite Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 305 Which of the following is an ordered, indexed data structure in JavaScript? A. Object B. Array C. Set D. Map Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 306 Which of these statements about Set in JavaScript is true? A. Set only stores unique values B. Set stores key-value pairs C. Set maintains insertion order of items D. Both a and c Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 307 How can you access the value for a specific key in a Map? A. map[key] B. map.get(key) C. map[key].value D. map.getValue(key) Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 308 What is the result of Array.from(new Set([1, 2, 2, 3, 4]))? A. [1, 2, 2, 3, 4] B. [1, 2, 3, 4] C. [2, 3, 4] D. [1, 3, 4] Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 309 Which of these data structures does not allow duplicate values by default? A. Array B. Object C. Set D. Map Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 310 What is a callback function in JavaScript? A. A function that is called automatically at the end of every function B. A function passed as an argument to another function and executed later C. A function that executes immediately upon definition D. A synchronous function that runs after another function completes Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 311 Which of the following correctly demonstrates a callback function? javascript function greet(name, callback) { console.log('Hello ' + name); callback(); } greet('Alice', function() { console.log('Callback executed'); }); A. Only logs "Hello Alice" B. Only logs "Callback executed" C. Logs "Hello Alice" and then "Callback executed" D. Throws an error Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 312 What is the main advantage of using callbacks in JavaScript? A. They allow synchronous code to execute faster B. They allow for more readable code C. They enable asynchronous execution, allowing code to continue running while waiting for another  process to complete D. They prevent errors from occurring in code Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 313 What is an example of a built-in JavaScript method that uses a callback function? A. forEach() B. map() C. setTimeout() D. All of the above Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 314 What is a common issue when using callbacks in JavaScript, especially when nesting multiple callbacks? A. Callback rejection B. Callback rejection C. Callback hell D. Callback cycle Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 315 Which of the following is a correct syntax for defining a function in JavaScript? A. function myFunc {... } B. let myFunc() = {... } C. function myFunc() {... } D. let myFunc[] = {... } Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 316 What is the output of the following code? javascript function add(a, b) { return a + b; } console.log(add (2, 3)); A. Undefined B. 23 C. 5 D. NaN Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 317 What keyword is used to define an arrow function in JavaScript? A. => B. -> C. : D. None of the above Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 318 Which of these functions immediately invokes itself upon definition? A. Anonymous function B. Named function C. IIFE (Immediately Invoked Function Expression) D. Callback function Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 319 What is the default return value of a function in JavaScript if no return statement is specified? A. Null B. Undefined C. NaN D. false Correct Answer: B Section: (none) Explanation Explanation/Reference: Objects QUESTION 320 Which of the following is a valid way to create an object in JavaScript? A. let obj = { } B. let obj = Object.create() C. let obj = new Object({ }) Correct Answer: AC Section: (none) Explanation Explanation/Reference: QUESTION 321 What is the result of the following code? javascript const person = { name: 'Alice', greet: function() { return 'Hello ' + this.name; } }; console.log(person.greet()); A. Hello Alice B. Hello undefined C. Undefined D. Throws an error Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 322 Which method is used to get an array of keys in an object? A. Object.values() B. Object.keys() C. Object.entries() D. Object.list() Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 323 How can you prevent modifications to an object in JavaScript? A. Object.lock() B. Object.preventExtensions() C. Object.seal() D. Object.freeze() Correct Answer: D Section: (none) Explanation Explanation/Reference: QUESTION 324 What will Object.assign() do when used on an object? A. It merges properties from one or more source objects into a target object B. It prevents extensions on the object C. It deep clones the object D. It deletes all properties in the object Correct Answer: A Section: (none) Explanation Explanation/Reference: QUESTION 325 What is the purpose of semicolons in JavaScript? A. To separate HTML from JavaScript B. To end statements (optional in most cases) C. To enclose a function D. To indicate variable declarations Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 326 What are reserved keywords in JavaScript? A. Words that can be used as variables B. Words that have a predefined meaning and cannot be used as identifiers C. Words only used in comments D. Any English word Correct Answer: B Section: (none) Explanation Explanation/Reference: QUESTION 327 Which of the following is a correct variable name in JavaScript? A. var 1name B. var name@ C. var $name D. var name% Correct Answer: C Section: (none) Explanation Explanation/Reference: QUESTION 328 What is an expression in JavaScript? A. value-producing piece of code B. Only a variable declaration C. Only a function call D. A line of code that does not produce a value Correct Answer: A Section: (none) Explanation Explanation/