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

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().

Refer to the following code:
Let sampleText = ‘The quick brown fox jumps’;
A developer needs to determine if a certain substring is part of a string.
Which three expressions return true for the given substring ?
Choose 3 answers

A.

sampleText.includes(‘fox’);

B.

sampleText.includes(‘ quick ’, 4);

C.

sampleText.includes(‘ Fox ’, 3)

D.

sampleText.includes(‘ fox ’);

E.

sampleText.includes(‘ quick ’) !== -1;

Given the code below:
Setcurrent URL ();
console.log(‘The current URL is: ‘ +url );
function setCurrentUrl() {
Url = window.location.href:What happens when the code executes?

A.

The url variable has local scope and line 02 throws an error.

B.

The url variable has global scope and line 02 executes correctly.

C.

The url variable has global scope and line 02 throws an error.

D.

The url variable has local scope and line 02 executes correctly.

A developer is required to write a function that calculates the sum of elements in an
array but is getting undefined every time the code is executed. The developer needs to find
what is missing in the code below.
Const sumFunction = arr => {
Return arr.reduce((result, current) => {
//
Result += current;
//
), 10);
);
Which option makes the code work as expected?

A.

Replace line 02 with return arr.map(( result, current) => (

B.

Replace line 04 with result = result +current;

C.

Replace line 03 with if(arr.length == 0 ) ( return 0; )

D.

Replace line 05 with return result;

developer creates a new web server that uses Node.js. It imports a server library that uses events and callbacks for handling server functionality.
The server library is imported with require and is made available to the code by a
variable named server. The developer wants to log any issues that the server has while
booting
up.
Given the code and the information the developer has, which code logs an error at boost
with an event?

A.

Server.catch ((server) => {
console.log(‘ERROR’, error);
});

B.

Server.error ((server) => {
console.log(‘ERROR’, error);
});

C.

Server.on (‘error’, (error) => {
console.log(‘ERROR’, error);
});

D.

Try{
server.start();
} catch(error) {
console.log(‘ERROR’, error);

Given the following code:
Let x =(‘15’ + 10)*2;
What is the value of a?

A.

3020

B.

1520

C.

50

D.

35

A developer creates an object where its properties should be immutable and prevent
properties from being added or modified.
Which method should be used to execute this business requirement ?

A.

Object.const()

B.

Object.eval()

C.

Object.lock()

D.

Object.freeze()

Given the following code:
document.body.addEventListener(‘ click ’, (event) => {
if (/* CODE REPLACEMENT HERE */) {
console.log(‘button clicked!’);
)
});
Which replacement for the conditional statement on line 02 allows a developer to
correctly determine that a button on page is clicked?

A.

Event.clicked

B.

e.nodeTarget ==this

C.

event.target.nodeName == ‘BUTTON’

D.

button.addEventListener(‘click’)

Refer to the expression below:

Let x = (‘1’ + 2) == (6 * 2);
How should this expression be modified to ensure that evaluates to false?

A.

Let x = (‘1’ + ‘ 2’) == ( 6 * 2);

B.

Let x = (‘1’ + 2) == ( 6 * 2);

C.

Let x = (1 + 2) == ( ‘6’ / 2);

D.

Let x = (1 + 2 ) == ( 6 / 2);

A developer wants to set up a secure web server with Node.js. The developer creates a
directory locally called app-server, and the first file is app-server/index.js
Without using any third-party libraries, what should the developer add to index.js to create
the
secure web server?

A.

const https =require(‘https’);

B.

const server =require(‘secure-server’);

C.

const tls = require(‘tls’);

D.

const http =require(‘http’);