Quiz about Certification Exam, JS Institute, JSA - Certified Associate JavaScript Programmer

Question 1

Which of the following methods will correctly perform a deep clone of an object in JavaScript?

Accepted Answer

JSON.parse(JSON.stringify(original))

Answer

original.clone()

Answer

Object.create(original)

Answer

Object.assign({}, original)

Question 2

Consider the following JavaScript code snippet: 1. const book = { 2. title: 'The Great Gatsby', 3. author: 'F. Scott Fitzgerald', 4. getSummary: function() { 5. return `${this.title} by ${this.author}`; 6. } 7. }; 8. 9. const getBookSummary = book.getSummary; 10. console.log(getBookSummary()); // What will this log to the console?

Accepted Answer

undefined by undefined

Answer

ReferenceError: title is not defined

Answer

null

Answer

The Great Gatsby by

Answer

Scott Fitzgerald', 4. getSummary: function() { 5. return `${this.title} by ${this.author}`; 6. } 7. }; 8. 9. const getBookSummary = book.getSummary; 10. console.log(getBookSummary()); // What will this log to the console? A. ReferenceError: title is not defined

Question 3

Consider the following JavaScript code snippet: 1. const obj = {
2. prop: 42,
3. func: function() {
4. return this.prop;
5. }
6. };
7.
8. const extractedFunc = obj.func;
9. console.log(extractedFunc()); // What will this log to the console?

Accepted Answer

undefined

Answer

42

Answer

TypeError: extractedFunc is not a function

Answer

null

Question 4

You have an array of tasks, where each task is an object with properties id
,
title
, and
completed
. Write a JavaScript function that returns a new array containing only the titles of the tasks that are not
completed, sorted alphabetically. Which of the following functions correctly implements this?

Accepted Answer

function getIncompleteTaskTitles(tasks) { return tasks.filter(task => !task.completed) .sort((a, b) => a.title.localeCompare(b.title)) .map(task => task.title);}

Answer

function getIncompleteTaskTitles(tasks) { return tasks.sort((a, b) => a.title.localeCompare(b.title)) .filter(task => !task.completed) .map(task => task.title);}

Answer

function getIncompleteTaskTitles(tasks) { return tasks.filter(task => task.completed) .map(task => task.title) .sort((a, b) => a.localeCompare(b));}

Answer

function getIncompleteTaskTitles(tasks) { return tasks.map(task => task.title) .filter(task => !task.completed) .sort((a, b) => a.localeCompare(b));}

Question 5

You have the following JavaScript code: 1. let config = {
2. server: \"localhost",
3. port: 8080,
4. options: {
5. secure: true,
6. timeout: 5000
7. },
8. features: {
9. feature1: "enabled",
10. feature2: "disabled"
11. }
12. };
13.
14. let key = "features";
15. let subKey = "feature1";
16. let dynamicKey = "timeout";
Which two of the following expressions correctly access the value
5000
from the
config
object?

Accepted Answer

config[\"options"]["timeout"]

Accepted Answer

config.options.timeout

Answer

config[key][subKey]

Answer

config[key].options[dynamicKey]

Question 6

Consider the following code snippet: 1. let sentence = new String(\" JavaScript "); 2. let trimmedSentence = sentence.trim().padEnd(15, "."); 3. console.log(trimmedSentence); What will be the output?

Accepted Answer

\"JavaScript....."

Answer

\"JavaScript..."

Answer

\"JavaScript"

Answer

\" JavaScript "

Question 7

You are tasked with writing a JavaScript function that takes multiple arguments and returns the sum of those arguments. If no arguments are provided, the function should return a default value of 10. Which
implementation correctly achieves this using default parameter values, the rest parameter, and the
spread operator?

Accepted Answer

function sum(defaultValue = 10, ...args) { return args.length ? args.reduce((a, b) => a + b, 0) : defaultValue;}

Answer

function sum(...args, defaultValue = 10) { return args.length ? args.reduce((a, b) => a + b, 0) : defaultValue;}

Answer

function sum(args = [10]) { return args.reduce((a, b) => a + b, 0);}

Answer

function sum(defaultValue, ...args = [10]) { return args.reduce((a, b) => a + b, 0);}

Question 8

Consider the following JavaScript code: 1. class BankAccount {
2. static totalAccounts = 0;
3.
4. constructor(owner, balance) {
5. this.owner = owner;
6. this.balance = balance;
7. BankAccount.incrementAccounts();
8. }
9.
10. static incrementAccounts() {
11. BankAccount.totalAccounts++;
12. }
13. }
14.
15. let account1 = new BankAccount('Alice', 1000);
16. let account2 = new BankAccount('Bob', 1500);
17. let account3 = new BankAccount('Charlie', 2000);
18.
19. console.log(BankAccount.totalAccounts);
What will be the output of
console.log(BankAccount.totalAccounts)
?

Accepted Answer

3

Answer

2

Answer

1

Answer

0

Question 9

Which two options correctly demonstrate different ways to create a new object with a name
property set to \"Gadget" without using a class?

Accepted Answer

const obj2 = new Object(); obj2.name = \"Gadget";

Accepted Answer

const obj1 = { name: \"Gadget" };

Answer

const obj5 = new Function();obj5.name = \"Gadget";

Answer

const obj6 = function() { this.name = \"Gadget"; };

Answer

const obj3 = Object.create({ name: \"Gadget" });

Question 10

Which of the following code snippets correctly initializes an array, adds a new element to the end, and removes the first element?

Accepted Answer

let arr = [1, 2, 3];arr.push(4);arr.shift();

Answer

let arr = [1, 2, 3];arr.unshift(4);arr.shift();

Answer

let arr = [1, 2, 3];arr.pop();arr.push(4);

Answer

let arr = [1, 2, 3];arr.push(4);arr.pop();

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