Question 1

Given the code below:

const copy = JSON.stringify([ new String(' false '), new Bollean( false ), undefined ]);

What is the value of copy?

Options :

A : -- [ \''false\'' , { } ]--

B : -- [ false, { } ]--

C : -- [ \''false\'' , false, undefined ]--

D : -- [ \''false\'' ,false, null ]--

Answer: D

Question 2

Given two expressions var1 and var2. What are two valid ways to return the logical AND

of the two expressions and ensure it is data type Boolean ?

Choose 2 answers:

Options :

A : Boolean(var1 && var2)

B : var1 && var2

C : var1.toBoolean() && var2toBoolean()

D : Boolean(var1) && Boolean(var2)

Answer: A,D

Question 3

A developer creates a simple webpage with an input field. When a user enters text in

the input field and clicks the button, the actual value of the field must be displayed in the

console.

Here is the HTML file content:

< input type ='' text'' value=''Hello'' name =''input'' >

< button type =''button'' >Display < /button >

The developer wrote the javascript code below:

Const button = document.querySelector('button');

button.addEvenListener('click', () => (

Const input = document.querySelector('input');

console.log(input.getAttribute('value'));

When the user clicks the button, the output is always ''Hello''.

What needs to be done make this code work as expected?

Options :

A : Replace line 04 with console.log(input .value);

B : Replace line 03 with const input = document.getElementByName('input');

C : Replace line 02 with button.addEventListener(''onclick'', function() {

D : Replace line 02 with button.addCallback(''click'', function() {

Answer: A

Question 4

Which javascript methods can be used to serialize an object into a string and deserialize

a JSON string into an object, respectively?

Options :

A : JSON.stringify and JSON.parse

B : JSON.serialize and JSON.deserialize

C : JSON.encode and JSON.decode

D : JSON.parse and JSON.deserialize

Answer: A

Question 5

A developer is creating a simple webpage with a button. When a user clicks this button

for the first time, a message is displayed.

The developer wrote the JavaScript code below, but something is missing. The

message gets displayed every time a user clicks the button, instead of just the first time.

01 function listen(event) {

02 alert ( 'Hey! I am John Doe') ;

03 button.addEventListener ('click', listen);

Which two code lines make this code work as required?

Choose 2 answers

Options :

A : On line 02, use event.first to test if it is the first execution.

B : On line 04, use event.stopPropagation ( ),

C : On line 04, use button.removeEventListener(' click'' , listen);

D : On line 06, add an option called once to button.addEventListener().

Answer: C,D

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