NodeJS Questions & Answers
Some common node.js questions and answers.
1. Which one is the node global object?
- A: log
- B: import
- C: process
- D: http
Answer
Answer: C
process is one of the node global object. Global objects are globally accessible. These are, **dirname, **filename, module, process, setTimeout, setInterval, setImmediate.
2. Which module is used to provide compression and decompression functionalities?
- A: net
- B: buffer
- C: zlib
- D: dns
Answer
Answer: C
zlib module provides compression(zip) and decompression(unzip) functionalities.
3. Which console method is used to show the stack trace?
- A: stack
- B: log
- C: trace
- D: debug
Answer
Answer: C
trace method is used to show the stack trace.
4. Which module would you use to get the server information?
- A: dns
- B: url
- C: net
- D: tls
Answer
Answer: A
dns module is used to get the server information.
5. Which one is used to read a file asynchronously?
- A: fs.getFile
- B: fs.read
- C: fs.readFile
- D: fs.get
Answer
Answer: C
fs.readFile is used to read a file asynchronously.
6. Which module would you use to encrypt data?
- A: crypto
- B: process
- C: encrypt
Answer
Answer: A
crypto module is used to encrypt data.
7. Which method is used to exit(kill) in node.js?
- A: kill
- B: exit
- C: stop
Answer
Answer: B
process.exit() is used to exit in node.js.
8. Which one is the core module of node?
- A: require
- B: import
- C: fs
- D: process
Answer
Answer: C
fs is a core module of node. Some of them are, buffer, crypto, dns etc.
9. Which command is used to tell node to run javascript strict mode in node repl?
- A: node -strict
- B: node --strict
- C: node --use-strict
- D: node -use--strict
Answer
Answer: C
node --use-strict will run node in javascript strict mode.
10. Which one is not a node repl command?
- A: .save
- B: .clear
- C: .help
- D: .find
Answer
Answer: D
.find is not a node repl command. The repl commands are, .break, .clear, .editor, .exit, .help, .load, .save.
11. Which one is an instance of Event Emitter?
- A: process
- B: fs
- C: http
- D: require
Answer
Answer: A
All objects that emit events are instances of the EventEmitter class. process emit events, so it is an instance of Event Emitter. You can check this via process instanceof require('events').EventEmitter.
12. How can you get the file name(with the directory) that you are working on?
- A: console.log(__dirname)
- B: console.log(filename)
- C: console.log(__filename)
- D: console.log(filename)
Answer
Answer: C
console.log(__filename) will show the file name.
13. How can you check if a module 'x' exist locally?
- A: require.get(x)
- B: require.resolve(x)
- C: require.find(x)
Answer
Answer: B
require.resolve(x) can give you the full path of the module.
14. Which one is not a correct property of process(global object)?
- A: .stdin
- B: .title
- C: .clear
- D: .execPath
Answer
Answer: C
.clear is not a property of process.
15. How can you get absolute path for a specific file app.js?
- A: __filename('app.js')
- B: path.absolute('app.js')
- C: path.resolve('app.js')
- D: __dirname('app.js')
Answer
Answer: C
path.resolve('app.js') will return the absolute path for app.js.
16. Which method is not a correct method for OS module?
- A: cpus()
- B: platform()
- C: type()
- D: version()
Answer
Answer: D
version() is not a correct method for os module.
17: Which one is a correct method to create child_process?
- A: fork()
- B: exec()
- C: spawn()
- D: all
Answer
Answer: D
all, there are three ways to create child_process, child_process.exec(), child_process.spawn() & child_process.fork().
18: Which DNS method returns an array of record types belonging to the specified hostname?
- A: resolve()
- B: lookupService()
- C: getServers()
- D: lookup()
Answer
Answer: A
resolve(), the resolve function returns an array of record types.
19: Which object holds arguments pass through a node command?
- A: cli.arguments
- B: process.arguments
- C: process.args
- D: process.argv
Answer
Answer: D
process.argv, holds arguments pass through a node command.
20: In node 12+, how can you make readFile a promise based method?
- A: const { readFile } = require('fs').promises
- B: const { readFile } = require('fs')
- C: const { readFile } = require('promises')
Answer
Answer: A
const { readFile } = require('fs').promises, by using this you can make readFile a promise based method.
readFile("./file.txt", { encoding: "utf8" })
.then((data) => console.log(data))
.catch((error) => console.error(error));21: Which one provides Event Loop?
- A: V8
- B: Libuv
- C: C++ bindings
Answer
Answer: B
Libuv library provides event loop.
22: APIs of Node.JS are
- A: Asynchronous
- B: Synchronous
- C: Both of the above
- D: None of the above
Answer
Answer: C
APIs of Node.JS are Asynchronous and Synchronous.
23: Which module is used to decode Buffer object into strings?
- A: decoder
- B: buffer
- C: string_buffer
- D: string_decoder
Answer
Answer: D
string_decoder is used to decode Buffer object into strings.
24: Which one is used to expose the node.js modules?
- A: module
- B: module.expose
- C: exports
- D: module.exports
Answer
Answer: D
Example:
module.exports.bar = "bar";25: To execute the code of index.js which method should use?
- A: npm index.js
- B: node.index.js
- C: node index.js
- D: npm run index.js
Answer
Answer: C
node filepath Is used to run any javascript file
26: Which module is used to serve static resources in Node.js?
- A: require
- B: node-resource
- C: fs
- D: node-static
Answer
Answer: D
You can use node-static module to serve static resources. This module is an HTTP static-file server module with built-in caching.
27: How to install a package (my-package) in node js?
- A: require my-package
- B: node install my-package
- C: npm install my-package
- D: none of the above
Answer
Answer: C
To install any package in node js just run npm install package-name (available in npmjs.com).
example: npm install my-package
28: Which one is used to create and consume custom events?
- A: NodeEvent
- B: EventEmitter
- C: Both of them
- D: none of the above
Answer
Answer: B
EventEmitter class lies in the events module. It can be accessible like this −
// Import events module
var events = require("events");
// Create an eventEmitter object
var eventEmitter = new events.EventEmitter();29: Valid form of route path in node.js?
- A: Regular expressions
- B: String
- C: String patterns
- D: All of them
Answer
Answer: D
You can use String, String pattern and regular expressions to form a route path.
30: Which module is used to create a server?
- A: fs
- B: http
- C: server
- D: none of the above
Answer
Answer: B
We use the http instance and call http.createServer() method to create a server instance
example:
var http = require("http");31: Input arguments for an asynchronous queue?
- A: Task function
- B: Concurrency value
- C: Both of them
- D: None of the above
Answer
Answer: C
Concurrency value and Task function are the main arguments that an asynchronous queue uses.
32: Which method is used to get the filename part of a file path?
- A: path.basename
- B: path.dirname
- C: path.parse
- D: path.join
Answer
Answer: A
path.basename is user to get the filename part of a file path.
33: The $ npm ls statement is used to list down all the _?
- A: Web application
- B: nodejs sample modules
- C: locally installed modules
- D: package modules
Answer
Answer: C
The $ npm ls statement is used to list down all the locally installed modules.
34: Which amongst the following mehtod is used to create instance of http module?
- A:
var http = require('http'); - B:
var http = new require('http'); - C:
var http = new http(); - D: None of these
Answer
Answer: A
var http = require('http'); is the methods of create instance of http module.
35: The __ core module is used to create a web server in Node.js.
- A:
fs - B:
url - C:
connect - D:
http
Answer
Answer: D
The http core module is used to create a web server in Node.js
36: Which of the following code gets length of a buffer buf?
- A: buf.length
- B: buf.size
- C: buf.length()
- D: buf.size()
Answer
Answer: A
buf.length returns size of a node buffer in bytes.
37: Which function is used to include modules in Node Js.
- A: include()
- B: require()
- C: attach()
- D: all
Answer
Answer: B
require(); function is used to include modules in Node Js.
38: Which of the following is a GUI-based debugging tool for Node.js?
- A: Core node debugger
- B: Console
- C: REPL
- D: Node Inspector
Answer
Answer: D
Node Inspector is a debugger interface for Node.js applications that uses the Blink Developer Tools (formerly WebKit Web Inspector).
39: Which command is used to silence all process warnings including deprecations for app.js?
- A: node app.js --trace-warnings
- B: node app.js --no-deprecation
- C: node app.js --no-warnings
- D: node app.js --trace-deprecation
Answer
Answer: C
node app.js --no-warnings is used to silence all process warnings including deprecations for app.js.
40: Which method is used to convert path segments into string using the platform-specific separator as a delimiter?
- A: path.join()
- B: path.parse()
- C: path.normalize()
- D: path.format()
Answer
Answer: A
path.join() method joins all given path segments together using the platform-specific separator as a delimiter, then normalizes the resulting path.
41: Which module is used to take advantage of multi-core systems?
- A: os
- B: dns
- C: stream
- D: cluster
Answer
Answer: D
cluster is used to take advantage of multi-core systems. As node.js runs as single threaded we can take advantage of multi-core systems using cluster module.
42: Which of the following are Node.js streams types?
- A: writable
- B: transform
- C: readable
- D: all of the above
Answer
Answer: D
There are four main types of streamsinNode. js: readable, writable, duplexandtransform`. Each stream is an eventEmitter instance that emits different events at several intervals.
43: How to test if two nodes are equal?
- A: isEqualNode()
- B: equal()
- C: ==
- D: None of the above
Answer: A
The Node. isEqualNode() method tests whether two nodes are equal.
44: Third-party packages can be install/update/delete using __.
- A: Node.exe
- B: Node Package Manager
- C: module.exports
- D: REPL
Answer: B
Third-party packages can be install/update/delete using NPM (Node Package Manager)
45: When you run JavaScript in a Node.js application, which element in a Node.js stack actually executes that JavaScript?
- A: the libuv library
- B: the VM (like V8 or Chakra)
- C: the c-ares library
- D: the repl module
Answer: B
The VM element will executes when run a Node.js applications.
46: What is the default scope in Node.js application?
- A: Global
- B: Global Function
- C: Local
- D: Local to object
Answer: C
Local is the default scope in the Node. js application.
47: Which method of fs module is used to close a file?
- A: fs.close(fd, callback)
- B: fs.closeFile(fd, callback)
- C: fs.closePath(fd, callback)
- D: None of the above.
Answer: A
fs.close(fd, callback) is the method which is used to close a file.
48: Which method of fs module is used to remove a directory?
- A: fs.deleteDirectory(path[, mode], callback)
- B: fs.rmdir(path, callback)
- C: fs.removeDirectory(path[, mode], callback)
- D: None of the above.
Answer: B
fs.rmdir(path, callback) is the method which is used to remove a directory.
49: Which of the following code gets length of a buffer buf?
- A: buf.length
- B: buf.size
- C: buf.length()
- D: buf.size()
Answer: A
buf.length returns size of a node buffer in bytes.
50: Which of the following platforms does Node.js support?
- A: Windows
- B: Macintosh
- C: Unix/Linux
- D: All of the above.
Answer: D
Node.js is supported on all of the above written operating systems.