JS1 Final

Question 1

Refer to the code below:
01 const exec = (item, delay) =>{
02 new Promise(resolve => setTimeout( () => resolve(item), delay)),
03 asyncfunction runParallel() {
04 Const (result1, result2, result3) = await Promise.all{
05[exec(‘x’,‘100’),exec(‘y’,500),exec(‘z’,‘100’)]
06);
07 return parallel is done: $(result1) $(result2)$(result3);
08 }
}
}

Which two statements correctly execute the runParallel () function?

Choose 2 answers

A. Async runParallel () .then(data);
B. runParallel ( ). done(function(data){
return data;
});
C. runParallel () .then(data);
D. runParallel () .then(function(data)
return data

Answer 1

Answer: B,D

Question 2

A developer needs to test this function:
01constsum3=(arr)=>(
02if(!arr.length)return0,
03 if (arr.length === 1) returnarr[0],
04 if(arr.length===2)returnarr[0]+arr[1],
05 return arr[0] + arr[1] + arr[2],
06 );

Which two assert statements are valid tests for the function?

Choose 2

A. console.assert(sum3(1, ‘2’)) == 12);
B. console.assert(sum3(0)) == 0);
C. console.assert(sum3(-3, 2 )) == -1);
D. console.assert(sum3(‘hello’, 2, 3, 4)) === NaN);

Answer 2

Answer: A,C

Question 3

Which statement phrases successfully?

A. JSON.parse ( ‘ foo ’);
B. JSON.parse ( “ foo ” );
C. JSON.parse( “ ‘ foo ’ ” );
D. JSON.parse(‘ “ foo ” ’);

Answer 3

Answer: D

Question 4

Refer to the code below:
01 let car1 = new promise((_, reject) =>
02 setTimeout(reject, 2000, “Car 1 crashed in”));
03 let car2 = new Promise(resolve => setTimeout(resolve, 1500, “Car 2
completed”));
04 let car3 = new Promise(resolve => setTimeout (resolve, 3000, “Car 3
Completed”));
05 Promise.race([car1, car2, car3])
06 .then(value =>(
07letresult = $(value)the race.`;
08 ))
09 .catch( arr => (
10 console.log(“Race is cancelled.”, err);
11 ));

What is the value of result when Promise.race executes?

A. Car 3 completed the race.
B. Car 1 crashed in the race.
C. Car 2 completed the race.
D. Race is cancelled

Answer 4

Answer: C

Question 5

Refer to the code below:
for(let number =2 ; number <= 5 ; number += 1 ) {
// insert code statement here
}
The developer needs to insert a code statement in the location shown.The code
statement has these requirements:

1. Does require an import
2. Logs an error when the boolean statement evaluates to false
3. WorksinboththebrowserandNode.js

Whichmeetthe requirements?

A. assert (number % 2 === 0);
B. console.error(number % 2 === 0);
C. console.debug(number % 2 === 0);
D. console.assert(number % 2 === 0);

Answer 5

Answer: D

Question 6

Adeveloperisworking on an ecommerce website where the delivery date is dynamically
calculated based on the current day.Thecodelinebelowisresponsibleforthis calculation.
Const deliveryDate = new Date();
Due to changes in the business requirements, the delivery date must now be today’s
date + 9 days.

Which code meets this new requirement?

A. deliveryDate.setDate(( new Date ( )).getDate () +9);
B. deliveryDate.setDate( Date.current () + 9);
C. deliveryDate.date = new Date(+9) ;
D. deliveryDate.date = Date.current () + 9;

Answer 6

A

Question 7

Which three statements are true about promises?

Choose 3 answers

A. The executor of a new Promise runs automatically.
B. A Promise has a .then() method.
C. A fulfilled or rejected promise will not change states.
D. A settled promise can become resolved.
E. A pending promise can become fulfilled, settled, or rejected.

Answer 7

Answer: B,C,E

Question 8

Given the code below:
01 function GameConsole (name) {
02 this.name =name;
03 }
04
05 GameConsole.prototype.load = function(gamename) {
06 console.log( ` $(this.name) is loading a game : $(gamename)…); 07 ) 08functionConsole 16Bit(name){ 09GameConsole.call(this, name); 10 } 11 Console16bit.prototype = Object.create ( GameConsole.prototype) ; 12 //insert codehere 13 console.log( $(this.name) is loading a cartridge game : $(gamename) …`);
14 }
15 const console16bit = new Console16bit(‘ SNEGeneziz ’);
16 console16bit.load(‘ Super Nonic 3x Force’);
Whatshouldadeveloperinsert atline 15tooutputthefollowingmessageusing the
method ?

> SNEGenezizisloading a cartridge game: Super Monic 3x Force . . .

A. Console16bit.prototype.load(gamename) = function() {
B. Console16bit.prototype.load = function(gamename) {
C. Console16bit = Object.create(GameConsole.prototype).load = function
(gamename) {
D. Console16bit.prototype.load(gamename) {

Answer 8

Answer: B

Question 9

A developer has the following array of student test grades:
Let arr = [ 7, 8, 5, 8, 9 ];
TheTeacher wants to double each score and then see an array of the students
who scored more than 15 points.
How should the developer implement the request?
A. Let arr1 = arr.filter(( val) => (return val > 15 )) .map (( num) => ( return num *2 ))
B. Let arr1 = arr.mapBy (( num) => (return num 2 )) .filterBy (( val ) => return val > 15 )) ;
C. Let arr1 = arr.map((num) => num2). Filter (( val) => val > 15);
D. Let arr1 = arr.map((num) => ( num *2)).filterBy((val) => ( val >15 ));

Answer 9

C

Question 10

A test has a dependency on database.query. During the test the dependency is replaced
with an object called data base with the method, query, that returns an array.The
developer needs to verify how many times the method was called and the arguments
used each time.

Which two test approaches describe the requirement?

Choose 2 answers
A. Integration
B. Black box
C. White box
D. Mocking

Answer 10

Answer: C,D

Question 11

Given the JavaScript below:
01 function filterDOM (searchString) {
02 const parsedSearchString = searchString && searchString.toLowerCase() ;
03 document.quesrySelectorAll(‘ .account’ ) . forEach(account => (
04const accountName = account.innerHTML.toLOwerCase();
05 account. Style.display = accountName.includes(parsedSearchString) ? /Insert
code/;
06 )};
07 }
Whichcodeshouldreplacetheplaceholder commentonline05tohideaccountsthatdo
not match the search string?

A. ‘ name ’ : ‘ block ’
B. ‘ Block ’ : ‘ none ’
C. ‘visible’:‘hidden’
D. ‘hidden’:‘visible’

Answer 11

B

Question 12

developer publishes a new version of a package with new features that do not break
backward compatibility. The previous version number was 1.1.3.
Following the semantic versioning format, what should the new package version number
be?

A.2.0.0
B.1.2.3
C.1.1.4
D. 1.2.0

Answer 12

D

Question 13

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().

Answer 13

C, D

Question 14

A developer uses aparsedJSONstring to work with user information as in the block below:
01 const userInformation={
02 “ id ” : “user-01”,
03 “email” : “user01@universalcontainers.demo”,
04 “age” : 25

Which two options access the email attribute in the object?

Choose 2 answers

A. userInformation(“email”)
B. userInformation.get(“email”)
C. userInformation.email
D. userInformation(email)

Answer 14

Answer: A,C

Question 15

Refer to the code below:
01 const server = require(‘server’);
02 /* Insert code here*/
Adeveloperimports a library that creates a webserver. The imported library uses events and callbacks to start the servers
Which code should be inserted at the line 03 to set up an event and start the web server?

A. Server.start ();
B. server.on(‘ connect ’ , ( port) =>{
console.log(‘Listening on ’ , port) ;})
C. server()
D. serve(( port) => (
E. console.log( ‘Listening on ’, port) ;

Answer 15

B

Question 16

Adeveloperwantstoiteratethroughanarrayofobjects andcounttheobjectsandcount
the objects whose property value, name,starts with the letter N.

Const arrObj = [{“name” : “Zach”} , {“name” : “Kate”},{“name” : “Alise”},{“name” : “Bob”},{“name” :
“Natham”},{“name” : “nathaniel”}
Refertothecodesnippetbelow:

01arrObj.reduce(( acc, curr)=>{
02//missing line02
02//missing line03
04 ). 0);

Which missing lines 02 and 03 return the correct count?

A. Constsum=curr.startsWith(‘N’)?1:0;
Return acc +sum
B. Const sum = curr.name.startsWith(‘N’) ? 1: 0;
Return acc +sum
C. Constsum=curr.startsWIth(‘N’)?1:0;
Return curr+ sum
D. Const sum = curr.name.startsWIth(‘N’) ? 1: 0;
Return curr+ sum

Answer 16

B

Question 17

A developer creates a class that represents a blog post based on the requirement that a
Post should have a body author and view count.

The Code shown Below:
Class Post {
// Insert code here
This.body =body
This.author = author;
this.viewCount = viewCount;
}
}

Which statement should be inserted in the placeholder online 02toallowfor a variable to be set
to a new instance of a Post with the three attributes correctly populated?

A. super (body, author, viewCount){
B. Function Post (body, author, viewCount){
C. constructor (body, author, viewCount){
D. constructor() {

Answer 17

C

Question 18

Which three options show valid methods for creating a fat arrow function?
Choose 3 answers

A. x => ( console.log(‘ executed ’);)
B. [] => ( console.log(‘ executed ’);)
C. () => ( console.log(‘ executed ’);)
D. X,y,z => ( console.log(‘ executed ’);)
E. (x,y,z) => ( console.log(‘ executed ’) ;)

Answer 18

A,C,E

Question 19

Refer to the code below:

const event = new CustomEvent(
//Missing Code
);

obj.dispatchEvent(event);

A developer needs to dispatch a custom event called update to send information about
record Id.

Which two options could a developer insert at the placeholder inline 02 to achieve this?

Choose 2 answers

A. ‘Update’ , (
recordId : ‘123abc’
(

B. ‘Update’ , ‘123abc’

C. { type : ‘update’, recordId : ‘123abc’ }

D. ‘Update’ , {
Details : {
recordId : ‘123abc’
}
}

Answer 19

Answer: A,D

Question 20

Refer to the code below:
Const pi = 3.1415326,

What is the data type of pi?

A. Double
B. Number
C. Decimal
D. Float

Answer 20

B

Question 21

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 )
D. Replace line 05 with return result;

Answer 21

D

Question 22

Given code below:
setTimeout (() => (
console.log(1);
). 0);
console.log(2);
New Promise ((resolve,reject)) = > (
setTimeout(() => (
reject(console.log(3));
). 1000);
)).catch(() => (
console.log(4);
));
console.log(5);
What is logged to the console?

A. 2 1 4 3 5
B. 2 5 1 3 4
C. 1 2 4 3 5
D. 1 2 5 3 4

Answer 22

B

Question 23

Which statement accurately describes the behavior of the async/ await keywords?

A. The associated class contains some asynchronous functions.
B. The associated function will always return a promise
C. The associated function can only be called via asynchronous methods
D. The associated sometimes returns a promise

Answer 23

B

Question 24

Adeveloperisdebugging awebserverthatusesNode.js Theserverhits a runtime error
every third request to an important endpoint on the web server.
The developer added a breakpoint to the start script, that is atindex.js at the root of the
server source code. The developer wants to make use of chromeDevToolstodebug.
Which command can be run toaccessDevTools and make sure the breakdown is hit ?

A. node -i index.js
B. Node –inspect-brk index.js
C. Node inspect index.js
D. Node –inspect index.js

Answer 24

D

Question 25

Refer to the code below:

Async funct on functionUnderTest(isOK) {
If (isOK) return ‘OK’ ;
Throw new Error(‘not OK’);
)
Which assertion accurately tests the above code?

A. Console.assert (await functionUnderTest(true), ‘ OK ’)
B. Console.assert (await functionUnderTest(true), ‘ not OK ’)
C. Console.assert (await functionUnderTest(true), ‘ not OK ’)
D. Console.assert (await functionUnderTest(true), ‘OK’)

Answer 25

D

Question 26

Consider type coercion, what does the following expression evaluate to?

True + 3 + ‘100’ + null

A. 104
B. 4100
C. ‘3100null’
D. ‘4100null’

Answer 26

D

Question 27

ADeveloperwrotethefollowing code to test a sum3 function that takes in an array of
numbers and returns the sum of the first three number in the array, The test passes:
Let res = sum2([1, 2, 3 ]) ;
console.assert(res === 6 );
Res = sum3([ 1, 2, 3, 4]);
console.assert(res=== 6);

Adifferentdevelopermadechangestothebehaviorofsum3toinsteadsumallofthenumbers
present in the array. The test passes: Whichtworesultsoccurwhenrunning thetestontheupdatedsum3function?
Choose 2 answers
A. The line 02 assertion passes.
B. The line 02 assertion fails
C. The line 05 assertion passes.
D. The line 05 assertion fails.

Answer 27

Answer: A,D

Question 28

Adevelopercreatesasimplewebpagewithaninputfield.Whenauserenterstextin
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?

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 28

A

Question 29

A developer createsanobjectwhereitspropertiesshouldbeimmutableandprevent
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()

Answer 29

D

Question 30

A developer has an ErrorHandler module that contains multiple functions.
What kind of export be leveraged so that multiple functions can be used?

A. Named
B. All
C. Multi
D. Default

Answer 30

A

Question 31

A team that works on a big project uses npm to deal with project dependencies.
A developer added a dependency does not get downloaded when they execute npm
install.

Whichtworeasonscouldbepossibleexplanationsforthis?

Choose 2 answers

A. The developer missed the option –add when adding the dependency.
B. The developer added the dependency as a dev dependency and
NODE_ENV Is set to production.
C. The developer missed the option –save when adding the dependency.
D. The developer didn’t pull back the current version

Answer 31

Answer: B,C

Question 32

A developer is asked to fix some bugs reported by users. To do that the developer adds
a breakpoint for debugging.

Function Car (maxSpeed, color){
This.maxspeed =masSpeed;
This.color = color;
Let carSpeed = document.getElementById(‘ CarSpeed’);

Debugger;

Let fourWheels =new Car (carSpeed.value, ‘red’);

Whenthecodeexecutionstops atthebreakpointonline06,whichtwotypesofinformationare
available in the browser console?

Choose 2 answers:

A. The values of the carSpeed and fourWheels variables
B. A variable displaying the number of instances created for the Car Object.
C. The style, eventlisteners and other attributes applied to the carSpeed DOM element
D. The information stored in the window.local Storage property

Answer 32

C, D

Question 33

AtUniversalContainers, every team has its own way of copying JavaScript objects. The
code Snippet shows an implementation from one team:

Function Person() {
this.firstName = “John”;
this.lastName = ‘Doe’;
This.name =() => (
console.log(‘Hello $(this.firstName) $(this.firstName)’);
)}
Const john = new Person ();
Const dan = JSON.parse(JSON.stringify(john));
dan.firstName =’Dan’;
dan.name();

What is the Output of the code execution?
A. Hello Dan Doe
B. Hello John DOe
C. TypeError: dan.name is not a function
D. TypeError: Assignment to constant variable

Answer 33

C

Question 34

Refer to the code below:
Let textValue = ’1984’;

Which code assignment shows a correct way to convert this string to an integer?

A. let numberValue = Number(textValue);
B. Let numberValue = (Number)textValue;
C. Let numberValue = textValue.toInteger();
D. Let numberValue = Integer(textValue);

Answer 34

A

Question 35

A developer writers the code below to calculate the factorial of a given number.
Function factorial(number) {
Return number + factorial(number -1);
}
factorial(3);
What is the result of executing line 04?

A. 0
B. 6
C. -Infinity
D. RuntimeError

Answer 35

D

Question 36

Given the following code:
Let x =null;
console.log(typeof x);
What is the output of the line 02?

A. “Null”
B. “X”
C. “Object”
D. “undefined”

Answer 36

C

Question 37

Which function should a developer use to repeatedly execute code at a fixed interval?

A. setIntervel
B. setTimeout
C. setPeriod
D. setInteria

Answer 37

A

Question 38

Refer to the code below:
Function changeValue(obj) {
Obj.value = obj.value/2;
}
Const objA = (value: 10);
Const objB = objA;
changeValue(objB);
Const result = objA.value;

What is the value of result after the code executes?
A. 10
B. Nan
C. 5
D. Undefined

Answer 38

C

Question 39

Given HTML below:
//<div>
//<div id =”row-uc”> Universal Container</div>
//<div id =”row-aa”>Applied Shipping</div>
//<div id =”row-bt”> Burlington Textiles </div>
//</div>

Which statement adds the priority-account CSS class to the universal Containers row ?
A. Document .querySelector(‘#row-uc’).classes.push(‘priority-account’);
B. Document .queryElementById(‘row-uc’).addclass(‘priority-account’);
C. Document .querySelector(‘#row-uc’).classList.add(‘priority-account’);
D. Document .querySelectorALL(‘#row-uc’).classList.add(‘priority-account’);

Answer 39

C

Question 40

Refer to the code below:
const addBy = ?
const addByEight =addBy(8);
const sum = addBYEight(50);
Which two functions can replace line 01 and return 58 to sum?

Choose 2 answers

A. const addBy = function(num1){
return function(num2){
return num1 + num2;
}
B. const addBy = function(num1){
return num1 +num2;
}
C. const addBy = (num1) => num1 + num2 ;
D. const addBY = (num1) => (num2) => num1 +num2;

Answer 40

A, D

Question 41

given a value which three options can a developer use to detect if the value isNaN?

Choose 2 answers!

A. value == NaN
B. Object.is(value, NaN)
C. value === Number.NaN
D. value ! == value
E. Number.isNaN(value)

Answer 41

Answer: A, E

Question 42

a developer wants to use a module named universalContainersLib and then call functions
from it.
Howshouldadeveloperimportevery function from the module andthencallthefuctionsfoo
and bar?

A. import * ad lib from ‘/path/universalContainersLib.js’;
lib.foo();
lib.bar();
B. import (foo, bar) from ‘/path/universalContainersLib.js’;
foo();
bar();
C. import all from ‘/path/universalContaineraLib.js’;
universalContainersLib.foo();
universalContainersLib.bar();
D. import * from ‘/path/universalContaineraLib.js’;
universalContainersLib.foo();
universalContainersLib.bar();

Answer 42

A

Question 43

Refer to the code snippet:
Function getAvailabilityMessage(item) {
If (getAvailability(item)){
Var msg =”Username available”;
}
Return msg;
}

A developer writes this code to return a message to user attempting to register a new
username. If the username is available, variable.

What is the return value of msg when get AvailabilityMessage (“newUserName”) is
executed and getAvailability(“newUserName”) returnsfalse?

A. “Username available”
B. “newUserName”
C. “Msg is not defined”
D. undefined

Answer 43

D

Question 44

Given the requirement to refactor the code above to JavaScript class format. Which class definition is correct?

function vehicle (name, price){
this.name = name;
this.price = price;
}

vehicle.prototype.priceinfo = function (){
return ‘cost of the $(this.name) is $(this.price);
}

var ford = new vehicle (‘Ford Mustang’, ‘20,000’);

A.
class vehicle {
constructor (name, price){
this.name = name;
this.price = price;
}
priceInfo(){
return ‘cost of the $(this.name) is $(this.price);
}
}

B.
class vehicle {
vehicle (name, price){
this.name = name;
this.price = price;
}
priceInfo(){
return ‘cost of the $(this.name) is $(this.price);
}
}

C.
class vehicle {
constructor (name, price){
name = name;
price = price;
}
priceInfo(){
return ‘cost of the $(this.name) is $(this.price);
}
}

D.

class vehicle {
constructor (){
this.name = name;
this.price = price;
}
priceInfo(){
return ‘cost of the $(this.name) is $(this.price);
}
}

Answer 44

A

Question 45

AdeveloperwantstosetupasecurewebserverwithNode.js. The developer creates a
directory locally called app-server, and the first file is app-server/index.js
Withoutusinganythird-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’);

Answer 45

A

Question 46

Given the code below:
const delay = sync delay => {
Return new Promise((resolve, reject) => {
setTimeout (resolve, delay);});};
const callDelay =async () =>{
const yup =await delay(1000);
console.log(1);

What is logged to the console?

A. 123
B. 132
C. 213
D. 231

Answer 46

D

Question 47

Refertothefollowingcode:
Let obj ={
Foo: 1,
Bar: 2
}
Let output =[],
for(let something in obj{
output.push(something);
}
console.log(output);

What is the output line 11?

A. [1,2]
B. [“bar”,”foo”]
C. [“foo”,”bar”]
D. [“foo:1”,”bar:2”]

Answer 47

C

Question 48

Refer to the code below?
Let searchString = ‘ look for this ’;

Which two options remove the whitespace from the beginning of searchString?

Choose 2 answers

A. searchString.trimEnd();
B. searchString.trimStart();
C. trimStart(searchString);
D. searchString.replace(/\s\s/, ‘’);

Answer 48

B,D

Question 49

Which three actions can be using the JavaScript browser console?
Choose 3 answers:

A. View and change DOM the page.
B. Display a report showing the performance of a page.
C. Run code that is not related to page.
D. view, change, and debug the JavaScript code of the page.
E. View and change security cookies.

Answer 49

A,C,D

Question 50

Aclasswaswrittentorepresentitemsforpurchaseinanonlinestore,andasecondclass
Representing itemsthatareonsaleatadiscountedprice.THeconstructorsetsthenametothe
first value passed in. The pseudocode is below:
Class Item {
constructor(name, price) {
… // Constructor Implementation
}
}
Class SaleItem extends Item {
constructor (name, price, discount) {
…//Constructor Implementation
}
}
There is a new requirement for a developer to implement a description method that will return a brief description for Item and SaleItem.

Let regItem =new Item(‘Scarf’, 55);
Let saleItem = new SaleItem(‘Shirt’ 80, -1);
Item.prototype.description =function(){return‘Thisisa’+this.name;
console.log(regItem.description());
console.log(saleItem.description());
SaleItem.prototype.description=function(){return‘Thisisadiscounted’+
this.name; }

console.log(regItem.description());
console.log(saleItem.description());

What is the output when executing the code above?

A. This is a Scarf
Uncaught TypeError: saleItem.description is not a function
This is aScarf
This is a discounted Shirt

B. Thisis a Scarf
This is a Shirt
Thisis a Scarf
This is a discounted Shirt

C. Thisis a Scarf
Thisis a Shirt
ThisisadiscountedScarf
Thisis adiscounted Shirt

D. This is aScarf
Uncaught TypeError: saleItem.description is not a function
This is a Shirt
This is a did counted Shirt

Answer 50

B

Question 51

Given the following code:

Let x =(‘15’ + 10)*2;

What is the value of a?
A. 3020
B. 1520
C. 50
D. 35

Answer 51

A

Question 52

Refer to the following code:
01 function Tiger(){
02 this.Type = ‘Cat’;
03 this.size = ‘large’;
04 }
05
06 lettony = new Tiger();
07 tony.roar = () =>{
08 console.log(‘They\’re great1’);
09 };
10
11 function Lion(){
12 this.type = ‘Cat’;
13 this.size = ‘large’;
14 }
15
16 letleo = new Lion();
17//Insertcodehere
18 leo.roar();

Which two statements could be inserted at line 17 to enable the function call on line 18?
Choose 2 answers.

A. Leo.roar = () => { console.log(‘They\’re pretty good:’);};
B. Object.assign(leo,Tiger);
C. Object.assign(leo,tony);
D. Leo.prototype.roar = () => { console.log(‘They\’re pretty good:’); };

Answer 52

A, C

Question 53

Which statement accurately describes an aspect of promises?

A. Arguments for the callback function passed to .then() are optional.
B. In a then() function returning results is not necessary since callbacks will catch the result of a previous promise.
C. .then() cannot be added after a catch.
D. .then() manipulates and returns the original promise.

Answer 53

A

Question 54

Given the code below:
Function myFunction(){
A = 5;
Var b =1;
}
myFunction();
console.log(a);
console.log(b);
What is the expected output?

A. Both lines 08 and 09 are executed, and the variables are outputted.
B. Line 08 outputs the variable, but line 09 throws an error.
C. Line 08 thrones an error, therefore line 09 is never executed.
D. Both lines 08 and 09 are executed, but the values outputted are undefined.

Answer 54

B

Question 55

WhichtwoconsolelogsoutputsNaN?

Choose 2 answers

A. console.log(10/ Number(‘5’));
B. console.log(parseInt(‘two’));
C. console.log(10/ ‘’five);
D. console.log(10/0);

Answer 55

B,C

Question 56

Given the following code:
Counter = 0;
constlogCounter = () => {
console.log(counter);
);
logCounter();
setTimeout(logCOunter, 1100);
setInterval(() => {
Counter++
logCounter();
}, 1000);

What is logged by the first four log statements?

A. 0 0 1 2
B. 0 1 2 3
C. 0 1 1 2
D. 0 1 2 2

Answer 56

C

Question 57

Refer to the code below:
Function Person(firstName, lastName, eyecolor) {
this.firstName =firstName;
this.lastName = lastName;
this.eyeColor =eyeColor;
}

Person.job = ‘Developer’;
const myFather = new Person(‘John’, ‘Doe’);
console.log(myFather.job);

What is the output after the code executes?

A. ReferenceError: eyeColor is not defined
B. ReferenceError: assignment to undeclared variable“Person”
C. Developer
D. Undefined

Answer 57

D

Question 58

A developer at Universal Containers creates a new landing page based on HTML,CSS, and JavaScript TO ensure that visitors have a good experience, a script named personalize Context needs to be executed when the webpage is fully loaded (HTML content and related files), in order to do some custom initialization.

Which statement should be used to call personalize website content based on the above
business requirement?

A. document.addEventListener(‘’onDOMContextLoaded’, personalizeWebsiteContext);
B. window.addEventListener(‘load’,personalizeWebsiteContext);
C. window.addEventListener(‘onload’, personalizeWebsiteContext);
D. Document.addEventListener(‘‘’DOMContextLoaded’ , personalizeWebsiteContext);

Answer 58

B

Question 59

In which situation should a developer include a try .. catch block around their function call ?

A. The function has an error that should not be silenced.
B. The function results in an out-of-memory issue.
C. The function might raise a runtime error that needs to be handled.
D. The function contains scheduled code.

Answer 59

C

Question 60

Adeveloperisleading the creation of a new browser application that will serve a single
page application. Theteamwantstouse anewwebframeworkMinimalsit.js. The Lead
developer wants to advocate for a more seasoned web framework that already has a
community around it.

Which two frameworks should the lead developer advocate for?

Choose 2 answers

A. Vue
B. Angular
C. Koa
D. Express

Answer 60

B, D

Question 61

Universal Containers recently launched its new landing page to host a crowd-funding
campaign. The page uses an external library to display some third-party ads. Once the page is fully loaded, it createsmorethan50newHTML items placed randomly inside theDOM, like the one in the code below:

//<div class='ad-libary-item ad-hidden' onload="myFunction()">
//<img src=”/ad-libary/ad01.gif”
//</div>

All the elements include the same ad-library-itemclass, They are hidden by default and they are randomly displayed while the user navigates through the page.

A. Use the DOM inspector to prevent the load event to be fired.
B. Use the brows to execute a script that removes all the elements containing the class ad-library item.
C. Use the DOM inspector to remove all the elements containing the class ad-library-item.
D. Use the browser console to execute a script that prevents the load event to be fired.

Answer 61

C

Question 62

Which code statement correctly retrieves and returns an object from localStorage?

A. const retrieveFromLocalStorage = () =>{
return JSON.stringify(window.localStorage.getItem(storageKey));
}
B. const retrieveFromLocalStorage = (storageKey) =>{
returnwindow.localStorage.getItem(storageKey);
}
C. const retrieveFromLocalStorage = (storageKey) =>{
return JSON.parse(window.localStorage.getItem(storageKey));
}
D. const retrieveFromLocalStorage = (storageKey) =>{
returnwindow.localStorage[storageKey];
}

Answer 62

C

Question 63

<input type=”file” onchange=”previewFile()”>
<img src=”” height=”200” alt=”Image Preview…”/>
The JavaScript portion is:
01 function previewFile(){
02 const preview = document.querySelector(‘img’);
03 const file =document.querySelector(‘input[type=file]’).files[0];
04 //line 4 code
05 reader.addEventListener(“load”, () =>{
06 preview.src = reader.result;
07 },false);
08 //line 8 code
09 }

Inlines 04 and 08 which code allows the user to select an image from their local
computer, and to display the image in the browser?

A. 04 const reader = new File();
08 if (file) URL.createObjectURL(file);

B. 04constreader=newFileReader();
08if(file)URL.createObjectURL(file);

C. 04 const reader = new File();
08 if (file) reader.readAsDataURL(file);

D. 04constreader=newFileReader();
08 if (file)reader.readAsDataURL(file);

Answer 63

D

Question 64

The developer creates a generic function to log custom messages in the console. To do this, the function below is implemented.
01 function logStatus(status){
02 console./Answer goes here/{‘Item status is: %s’, status};
03 }

Which three console logging methods allow the use of string substitution in line 02?

A. Assert
B. Log
C. Message
D. Info
E. Error

Answer 64

Answer: B,D,E

Question 65

Adeveloperwrotethefollowingcode:
01 let X = object.value;
02
03 try {
04 handleObjectValue(X);
05 } catch (error){
06 handleError(error);
07 }
The developer has a getNextValue function to execute after handleObjectValue(), but
does not want to execute getNextValue() if an error occurs.

How can the developer change the code to ensure this behavior?

A. 03 try{
04 handleObjectValue(x);
05 } catch(error){
06 handleError(error);
07 } then{
08 getNextValue();
09 }

B. 03 try{
04 handleObjectValue(x);
05 } catch(error){
06 handleError(error);
07 } finally{
08 getNextValue();
10 }

C. 03 try{
04 handleObjectValue(x);
05 } catch(error){
06 handleError(error);
07 }
08 getNextValue();

D. 03 try {
04 handleObjectValue(x)
05 ……………………

Answer 65

D

Question 66

Given the code above which three properties are set pet1?

function Animal(size, type){
this.size = size || “small”;
this.type = type || “Animal”;
this.canTalk = false;
}

let Pet = function (size, type, name, owner){
animal.call(this, size, type);
this.name = name;
this.owner = owner;
}

pet.prototype = Object.create(Animal.prototype);

let pet1 = new pet();

console.log(pet1);
Choose 3 answers:
A. Name
B. canTalk
C. Type
D. Owner
E. Size

Answer 66

B,C,E

Question 67

Refer to the code below:
Let car1 = new Promise((_ , reject) =>
setTimeout(reject,2000,“car1crashedin”=>
Let car2 =new Promise(resolve => setTimeout(resolve, 1500, “car 2 completed”)
Let car3 =new Promise(resolve => setTimeout(resolve, 3000, “car 3 completed”)
Promise.race(( car1, car2, car3))
.then (value => (
Let result = ‘$(value) the race.’;)}
.catch(arr => {
console.log(“Race is cancelled.”, err);
});
What is the value of result when Promise.race executes?
A. Car 3 completes the race
B. Car 2 completed the race.
C. Car 1 crashed in the race.
D. Race is cancelled.

Answer 67

B

Question 68

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;

Answer 68

Answer: A, D, E

Question 69

Given two expressions var1 and var2. What are two valid ways to return the logical AND
of the two expressions and ensure its data type is Boolean?

Choose 2 answers:

A. Boolean(var1 && var2)
B. var1 && var2
C. var1.toBoolean() && var2toBoolean()
D. Boolean(var1) && Boolean(var2)

Answer 69

A D

Question 70

CloudKicks has a class to represent items for sale in an online store, as shown below:
ClassItem{
constructor (name, price){
this.name = name;
this.price = price;
}
formattedPrice(){
return ‘s’ + String(this.price);}}
A new business requirement comes in that requests a ClothingItemclass that should have all of the properties and methods of the Item class but will also have properties that are specific to clothes.

Which line of code properly declares the clothingItemclass such that it inherits from
Item?
A. Class ClothingItem implements Item{
B. Class ClothingItem {
C. Class ClothingItem super Item {
D. Class ClothingItem extends Item {

Answer 70

D

Question 71

Refer to the code below:

let greetings = ‘Goodbye’;
let salutation = ‘Hello, hello, hello’;

try{
greeting = ‘Hello’;
decodeURI (‘%%%’);
salutation = ‘Goodbye’
}catch(error){
salutation = ‘I say hello’;
}finally{
salutation = ‘Hello, Hello’;
}

Line 05 causes an error.
What are the values of greeting and salutation once code completes?

A. Greeting is Hello and salutation is Hello, Hello.
B. Greeting is Goodbye and salutation is Hello, Hello.
C. Greeting is Goodbye and salutation is I say Hello.
D. Greeting is Hello and salutation is I say hello.

Answer 71

A

Question 72

Refer to the code below:
Let str = ‘javascript’;
Str[0] = ‘J’;
Str[4] = ’S’;
After changing the string index values, the value of str is ‘javascript’. What is the reason for this value:

A. Non-primitive values are mutable.
B. Non-primitive values are immutable.
C. Primitive values are mutable.
D. Primitive values are immutable.

Answer 72

D

Question 73

Refer to the code below:
new Promise((resolve, reject) => { const fraction = Math.random();
if( fraction >0.5) reject(“fraction > 0.5, “ + fraction); resolve(fraction);
})
.then(() =>console.log(“resolved”))
.catch((error) => console.error(error))
.finally(() => console.log(“ when am I called?”));

When does Promise.finally on line 08 get called?

A. When rejected
B. When resolved and settled
C. When resolved
D. When resolved or rejected

Answer 73

D

Question 74

Refer to the following array:
Let arr1 = [ 1, 2, 3, 4, 5 ];

Which two lines of code result in a second array, arr2 being created such that arr2 is not a reference to arr1?

A. Let arr2 = arr1.slice(0, 5);
B. Let arr2 = Array.from(arr1);
C. Let arr2 = arr1;
D. Let arr2 = arr1.sort();

Answer 74

A,B

Question 75

Refer to code below:
Function muFunction(reassign){
Let x = 1; var y = 1;

if( reassign )
{ Let x= 2; Var y = 2; console.log(x); console.log(y);
}
console.log(x);
console.log(y);
}

What is displayed when myFunction(true) is called?
A. 2 2 1 1
B. 2 2 undefined undefined
C. 2 2 1 2
D. 2 2 2 2

Answer 75

C

Question 76

A developer wants to create an object from a function in the browser using the code below:

Function Monster() { this.name = ‘hello’ };
Const z = Monster();
What happens due to the lack of the new keyword on line 02?

A. The z variable is assigned the correct object.
B. The z variable is assigned the correct object but this.name remains undefined.
C. Window.name is assigned to ‘hello’ and the variable z remains undefined.
D. Window.m is assigned the correct object.

Answer 76

C

Question 77

developer removes the HTML class attribute from the checkout button, so now it is simply:
<button>Checkout</button>.
There is a test to verify the existence of the checkout button, however, it looks for a button with class= “blue”. The test fails because no such button is found. Which type of test category describes this test?

A. True positive
B. True negative
C. False positive
D. False negative

Answer 77

D

Question 78

Which two code snippets show working examples of a recursive function? Choose 2 answers

A. Let countingDown = function(startNumber) { If ( startNumber >0) { console.log(startNumber) ;
return countingDown(startNUmber);
} else {
return startNumber;
}};

B. Function factorial ( numVar ) { If (numVar < 0) return; If ( numVar === 0 ) return 1; return numVar -1;

C. Const sumToTen = numVar => {
If (numVar < 0) Return; return sumToTen(numVar + 1)};

D. Const factorial =numVar => {
If (numVar < 0) return; If ( numVar === 0 ) return 1;
return numVar * factorial ( numVar - 1 );
};

Answer 78

A,D

Question 79

Refer to the HTML below:
//<div id=”main”>
//<ul>
//<li>Leo</li>
//<li>Tony</li>
//<li>Tiger</li>
//</ul>
//</div>
Which JavaScript statement results in changing “ Tony” to “Mr. T.”?

A. document.querySelectorAll(‘$main $TONY’).innerHTML = ’ Mr. T. ’;
B. document.querySelector(‘$main li:second-child’).innerHTML = ’ Mr. T. ’;
C. document.querySelector(‘$main li.Tony’).innerHTML = ’ Mr. T. ’;
D. document.querySelector(‘$main li:nth-child(2)’),innerHTML = ’ Mr. T. ’;

Answer 79

D

Question 80

Considering type coercion, what does the following expression evaluate?

True + ‘13’ + NaN

A. ‘ 113Nan ’
B. 14
C. ‘ true13 ’
D. ‘ true13NaN ’

Answer 80

D

Question 81

A developer wrote a fizzbuzz function that when passed in a number, returns the following:
● ‘Fizz’ if the number is divisible by 3.
● ‘Buzz’ if the number is divisible by 5.
● ‘Fizzbuzz’ if the number is divisible by both 3 and 5.
● Empty string if the number is divisible by neither 3 or 5.

Which two test cases will properly test scenarios for the fizzbuzz function?

Choose 3 answers

A. let res = fizzbuzz(5); console.assert ( res === ‘ ’ );
B. let res = fizzbuzz(15); console.assert ( res === ‘ fizzbuzz ’ )
C. let res = fizzbuzz(Infinity); console.assert ( res === ‘ ’ )
D. let res = fizzbuzz(3); console.assert ( res === ‘ fizz ’ )

Answer 81

Answer: B, C, D

Question 82

A developer has code that calculates a restaurant bill, but generates incorrect answers while testing the code:
function calculateBill ( items ) {
let total = 0;
total += findSubTotal(items);
total += addTax(total);
total += addTip(total);
return total;
}
Which option allows the developer to step into each function execution within calculateBill?

A. Using the debugger command on line 05.
B. Using the debugger command on line 03
C. Calling the console.trace (total) method on line 03.
D. Wrapping findSubtotal in a console.log() method.

Answer 82

A

Question 83

The developer has a function that prints “Hello” to an input name. To test this, the developer created a function that returns “World”. However, the following snippet does not print “ Hello World”.

const sayHello = (name) => {
console.log(“Hello”, name());
};

const world = () => {
return “world”;
};

sayhello(world);

What can the developer do to change the code to print “Hello World”?

A. Change line 7 to ) () ;
B. Change line 2 to console.log(‘Hello’ , name() );
C. Change line 9 to sayHello(world) ();
D. Change line 5 to function world ( ) {

Answer 83

B

Question 84

A developer has the function, shown below, that is called when a page loads. function onload() {
console.log(“Page has loaded!”);
}
Where can the developer see the log statement after loading the page in the browser?

A. Terminal running the web server.
B. Browser performance toots
C. Browser javaScript console
D. On the webpage.

Answer 84

C

Question 85

Refer to the code below: let sayHello = () => {
console.log (‘Hello, world!’);
};

Which code executes sayHello once, two minutes from now?

A. setTimeout(sayHello, 12000);
B. setInterval(sayHello, 12000);
C. setTimeout(sayHello(), 12000);
D. delay(sayHello, 12000);

Answer 85

A

Question 86

What is the result of the code block?

A. The console logs only ‘flag’.
B. The console logs ‘flag’ and another flag.
C. An error is thrown.
D. The console logs ‘flag’ and then an error is thrown.

Answer 86

D

Question 87

Refer to the following code that imports a module named utils: import (foo, bar) from ‘/path/Utils.js’; foo() ; bar() ;

Which two implementations of Utils.js export foo and bar such that the code above runs without error?
Choose 2 answers

A. // FooUtils.js and BarUtils.js exist
Import (foo) from ‘/path/FooUtils.js’;
Import (boo) from ‘ /path/NarUtils.js’;

B. const foo = () => { return ‘foo’ ; } const bar = () => { return ‘bar’ ; } export { bar, foo }

C. Export default class { foo() { return ‘foo’ ; }
bar() { return ‘bar’ ; }
}

D. const foo = () => { return ‘foo’;} const bar = () => {return ‘bar’; } Export default foo, bar;

Answer 87

B,C

Question 88

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);
}

Answer 88

C

Question 89

Refer to the following code:

function test (val) {
If (val === undefined) {
return ‘Undefined values!’ ;
}
if (val === null) {
return ‘Null value! ’;
}
return val;
}
Let x; test(x);
What is returned by the function call on line 13?

A. Undefined
B. Line 13 throws an error.
C. ‘Undefined values!’
D. ‘Null value!’

Answer 89

C

Question 90

Which code statement below correctly persists an objects in local Storage ?

A. const setLocalStorage = (storageKey, jsObject) => { window.localStorage.setItem(storageKey, JSON.stringify(jsObject));
}
B. const setLocalStorage = ( jsObject) => { window.localStorage.connectObject(jsObject));
}
C. const setLocalStorage = ( jsObject) => {
window.localStorage.setItem(jsObject);
}
D. const setLocalStorage = (storageKey, jsObject) => { window.localStorage.persist(storageKey, jsObject);
}

Answer 90

A

Question 91

Given the code below:

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

What is the value of copy?

A. – [ \”false\” , { } ]–
B. – [ false, { } ]–
C. – [ \”false\” , false, undefined ]–
D. – [ \”false\” ,false, null ]–

Answer 91

D

Question 92

The developer wants to test the array shown: const arr = Array(5).fill(0)
Which two tests are the most accurate for this array? Choose 2 answers:

A. console.assert( arr.length === 5 );
B. arr.forEach(elem => console.assert(elem === 0)) ;
C. console.assert(arr[0] === 0 && arr[ arr.length] === 0);
D. console.assert (arr.length >0);

Answer 92

A,B

Question 93

A developer receives a comment from the Tech Lead that the code given below has error:

const monthName = ‘July’;
const year = 2019;
if(year === 2019) {
monthName = ‘June’;
}
Which line edit should be made to make this code run?

A. 01 let monthName =’July’;
B. 02 let year =2019;
C. 02 const year = 2020;
D. 03 if (year == 2019) {

Answer 93

A

Question 94

Refer to the following code:
//<html lang=”en”>
//<body>
//<div onclick = “console.log(‘Outer message’) ;”>
//<button id =”myButton”>CLick me<button>
//</div>
//</body>

 
function displayMessage(ev) { 
ev.stopPropagation(); 
console.log(‘Inner message.’); 
} 
const elem = document.getElementById(‘myButton’); elem.addEventListener(‘click’ , displayMessage); 

</html>
What will the console show when the button is clicked?</button>

A. Outer message
B. Outer message Inner message
C. Inner message Outer message
D. Inner message

Answer 94

D

Question 95

function foo () {
const a =2; function bat() {
console.log(a);
}
return bat;
}
Why does the function bar have access to variable a ?

A. Inner function’s scope
B. Hoisting
C. Outer function’s scope
D. Prototype chain

Answer 95

C

Question 96

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’)

Answer 96

C

Question 97

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’)

Answer 97

C

Question 98

Universal Container(UC) just launched a new landing page, but users complain that the website is slow. A developer found some functions that cause this problem. To verify this, the developer decides to do everything and log the time each of these three suspicious functions consumes.

console.time(‘Performance’);
maybeAHeavyFunction();
thisCouldTakeTooLong();
MaybeThisOne();
console.endTime(‘Performance’);

Which function can the developer use to obtain the time spent by every one of the three functions?

A. console.timeLog()
B. console.getTime()
C. console.trace()
D. console.timeStamp()

Answer 98

A

Question 99

Refer to the code below:

console.log(‘’start);
Promise.resolve(‘Success’) .then(function(value){
console.log(‘Success’);
});
console.log(‘End’);

What is the output after the code executes successfully?

A. End Start
Success
B. Start
Success
End
C. Start
End
Success
D. Success
Start
End

Answer 99

C

Question 100

Refer to HTML below:
<div id =”main”>
<div id = “ card-00”>This card is smaller.</div>
<div id = “card-01”>The width and height of this card is determined by its contents.</div>
</div>
Which expression outputs the screen width of the element with the ID card-01?
A. document.getElementById(‘ card-01 ’).getBoundingClientRest().width
B. document.getElementById(‘ card-01 ’).style.width
C. document.getElementById(‘ card-01 ’).width
D. document.getElementById(‘ card-01 ’).innerHTML.lenght

Answer 100

A

Question 101

developer is trying to convince management that their team will benefit from using
Node.js for a backend server that they are going to create. The server will be a web server that handles API requests from a website that the team has already built using HTML, CSS, and JavaScript.
Which three benefits of Node.js can the developer use to persuade their manager? Choose 3 answers:

A. Installs with its own package manager to install and manage third-party libraries.
B. Ensures stability with one major release every few years.
C. Performs a static analysis on code before execution to look for runtime errors.
D. Executes server-side JavaScript code to avoid learning a new language.
E. Uses non-blocking functionality for performant request handling .

Answer 101

A,C,E

Question 102

A developer is wondering whether to use, Promise.then or Promise.catch, especially when a Promise throws an error?

Which two promises are rejected?

Which 2 are correct?

A. Promise.reject(‘cool error here’).then(error => console.error(error));
B. Promise.reject(‘cool error here’).catch(error => console.error(error));
C. New Promise((resolve, reject) => (throw ‘cool error here’}).catch(error => console.error(error)) ;
D. New Promise(() => (throw ‘cool error here’}).then(null, error => console.error(error)));

Answer 102

B,C

Question 103

Refer to code below:

function Person() {
this.firstName = ’John’;
}
Person.prototype ={
Job: x => ‘Developer’
};

const myFather = new Person();
const result =myFather.firstName + ‘ ‘ + myFather.job();

What is the value of the result after line 10 executes?

A. Error: myFather.job is not a function
B. Undefined Developer
C. John undefined
D. John Developer

Answer 103

A

Question 104

Universal Containers (UC) notices that its application that allows users to search for accounts makes a network request each time a key is pressed. This results in too many requests for the server to handle.

● Address this problem, UC decides to implement a debounce function on string change handler.

What are three key steps to implement this debounce function? Choose 3 answers:

A. If there is an existing setTimeout and the search string change, allow the existing setTimeout to finish, and do not enqueue a new setTimeout.
B. When the search string changes, enqueue the request within a setTimeout.
C. Ensure that the network request has the property debounce set to true.
D. If there is an existing setTimeout and the search string changes, cancel the existing setTimeout using the persisted timerId and replace it with a new setTimeout.
E. Store the timeId of the setTimeout last enqueued by the search string change handle.

Answer 104

Answer: A, B, C

Question 105

Refer to the following object:

const cat ={ firstName: ‘Fancy’, lastName: ‘ Whiskers’,
Get fullName() {
return this.firstName + ‘ ‘ + this.lastName;
}
};

How can a developer access the fullName property for cat?

A. cat.fullName
B. cat.fullName()
C. cat.get.fullName
D. cat.function.fullName()

Answer 105

A

Question 106

Refer to following code:

class Vehicle { constructor(plate) {
This.plate =plate;
}
}
Class Truck extends Vehicle { constructor(plate, weight) {
//Missing code
This.weight = weight;
}
displayWeight() {

console.log(‘The truck ${this.plate} has a weight of ${this.weight} lb.’);}}

Let myTruck = new Truck(‘123AB’, 5000);
myTruck.displayWeight();

Which statement should be added to line 09 for the code to display ‘The truck 123AB has a weight of 5000lb.’?

A. Super.plate =plate;
B. super(plate);
C. This.plate =plate;
D. Vehicle.plate = plate;

Answer 106

B

Question 107

Which option is a core Node,js module?

A. Path
B. Ios
C. Memory
D. locate

Answer 107

A

Question 108

Refer to the code snippet below:

Let array = [1, 2, 3, 4, 4, 5, 4, 4];
For (let i =0; i < array.length; i++){
if (array[i] === 4) {
array.splice(i, 1);
}
}
What is the value of the array after the code executes?

A. [1, 2, 3, 4, 5, 4, 4]
B. [1, 2, 3, 4, 4, 5, 4]
C. [1, 2, 3, 4, 5, 4]
D. [1, 2, 3, 5]

Answer 108

C

Question 109

Which option is true about the strict mode in imported modules?

A. Add the statement use non-strict, before any other statements in the module to enable not-strict mode.
B. You can only reference notStrict() functions from the imported module.
C. Imported modules are in strict mode whether you declare them as such or not.
D. Add the statement use strict =false; before any other statements in the module to enable not- strict mode.

Answer 109

B

Question 110

Teams at Universal Containers (UC) work on multiple JavaScript projects at the same time.
UC is thinking about reusability and how each team can benefit from the work of others.

Going open-source or public is not an option at this time.

Which option is available to UC with npm?

A. Private packages can be scored, and scopes can be associated to a private registries.
B. Private registries are not supported by npm, but packages can be installed via URL. C. Private packages are not supported, but they can use another package manager like yarn.
D. Private registries are not supported by npm, but packages can be installed via git.

Answer 110

A

Question 111

Refer to code below:
Let first = ‘who’;
Let second = ‘what’;

Try{ Try{
Throw new error(‘Sad trombone’);
}catch (err){
First =’Why’;
}finally {
Second =’when’;
} catch (err) {
Second =’Where’;
}
What are the values for the first and second once the code executes?

A. First is Who and second is When
B. First is why and second is where
C. First is who and second is where
D. First is why and second is when

Answer 111

D

Question 112

Which javascript methods can be used to serialize an object into a string and deserialize a JSON string into an object, respectively?

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 112

A

Question 113

Refer to following code block:
Let array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,];
Let output =0; For (let num of array){ if (output >0){
Break;
}
if(num % 2 == 0){
Continue;
}
Output +=num;
What is the value of output after the code executes?

A. 16
B. 36
C. 11
D. 25

Answer 113

A

Question 114

Refer to the code below:
//<html lang=”en”>
//<table onclick=”console.log(Table log’);”>
//<tr id=”row1”>
//<td>Click me!</td>
//</tr>
//<table>

 
function printMessage(event) { console.log(‘Row log’); 
} 
Let elem = document.getElementById(‘row1’); elem.addEventListener(‘click’, printMessage, false); 

</html>

Which code change should be made for the console to log only Row log when ‘Click me! ’ is clicked?

A. Add.event.stopPropagation(); to window.onLoad event handler.
B. Add event.stopPropagation(); to printMessage function.
C. Add event.removeEventListener(); to window.onLoad event handler.
D. Add event.removeEventListener(); toprintMessage function.

Answer 114

B

Question 115

Refer to code below:
Let a =’a’;
Let b;
// b = a;
console.log(b);

What is displayed when the code executes?

A. ReferenceError: b is not defined
B. A
C. Undefined
D. Null

Answer 115

C

Question 116

Refer to the code below:

let timeFunction =() => {
console.log(‘Timer called.”);
};
let timerId = setTimeout (timedFunction, 1000);

Which statement allows a developer to cancel the scheduled timed function?

A. removeTimeout(timedFunction);
B. removeTimeout(timerId);
C. clearTimeout(timerId);
D. clearTimeout(timedFunction);

Answer 116

C

Question 117

Refer to the code below:

Let inArray =[ [ 1, 2 ] , [ 3, 4, 5 ] ];

Which two statements result in the array [1, 2, 3, 4, 5] ?

Choose 2 answers
A. [ ]. Concat.apply ([ ], inArray);
B. [ ]. Concat (… inArray);
C. [ ]. concat.apply(inArray, [ ]);
D. [ ]. concat ( [ ….inArray ] );

Answer 117

A,B

Question 118

developer has a web server running with Node.js. The command to start the web server is node server,js. The web server started having latency issues. Instead of a one second turn around for web requests, the developer now sees a five second turnaround, Which command can the web developer run to see what the module is doing during the latency period?

A. DEBUG = http, https node server.js
B. NODE_DEBUG =http, https node server.js
C. DEBUG =true node server.js
D. NODE_DEBUG =true node server.js

Answer 118

C

Question 119

Refer to the code below:

Let foodMenu1 = [‘pizza’, ‘burger’, ‘French fries’];

Let finalMenu = foodMenu1;

finalMenu.push(‘Garlic bread’);

What is the value of foodMenu1 after the code executes?

A. [ ‘pizza’,’Burger’, ‘French fires’, ‘Garlic bread’]
B. [ ‘pizza’,’Burger’, ‘French fires’]
C. [ ‘Garlic bread’ , ‘pizza’,’Burger’, ‘French fires’ ]
D. [ ‘Garlic bread’]

Answer 119

B

Question 120

Refer to code below:

Let productSKU = ‘8675309’ ;

A developer has a requirement to generate SKU numbers that are always 19 characters long, starting with ‘sku’, and padded with zeros.

Which statement assigns the values sku0000000008675309 ?

A. productSKU = productSKU .padStart (19. ‘0’).padstart(‘sku’);
B. productSKU = productSKU .padEnd (16. ‘0’).padstart(‘sku’);
C. productSKU = productSKU .padEnd (16. ‘0’).padstart(19, ‘sku’);
D. productSKU = productSKU .padStart (16. ‘0’).padstart(19, ‘sku’);

Answer 120

D

Question 121

A developer is setting up a new Node.js server with a client library that is built using events and callbacks. The library:

● Will establish a web socket connection and handle receipt of messages to the server
● Will be imported with require, and made available with a variable called we.

The developer also wants to add error logging if a connection fails.
Given this info, which code segment shows the correct way to set up a client with two events that listen at execution time?

A. ws.connect (( ) => { console.log(‘connected to client’); }).catch((error) => { console.log(‘ERROR’ , error); }};

B. ws.on (‘connect’, ( ) => {
console.log(‘connected to client’);
ws.on(‘error’, (error) => {
console.log(‘ERROR’ , error);
});
});

C. ws.on (‘connect’, ( ) => {
console.log(‘connected to client’);
}};
ws.on(‘error’, (error) => {
console.log(‘ERROR’ , error);
}};

D. try{ ws.connect (( ) => {
console.log(‘connected to client’); });
} catch(error) { console.log(‘ERROR’ , error); };
}

Answer 121

C

Question 122

Refer to the code snippet below:
Let array = [1, 2, 3, 4, 4, 5, 4, 4];
For (let i =0; i < array.length; i++) {
if (array[i] === 4) {
array.splice(i, 1);
}
}
What is the value of array after the code executes?

A. [1, 2, 3, 4, 5, 4, 4]
B. [1, 2, 3, 4, 4, 5, 4]
C. [1,2,3,5]
D. [1,2,3,4,5,4]

Answer 122

D

Question 123

Refer to HTML below:
//<p>
The current status of an Order:
<span id =”status”> In Progress </span>
</p>.

Which JavaScript statement changes the text ‘In Progress’ to ‘Completed’ ?

A. document.getElementById(“status”).Value = ’Completed’ ;
B. document.getElementById(“#status”).innerHTML = ’Completed’ ;
C. document.getElementById(“status”).innerHTML = ’Completed’ ;
D. document.getElementById(“.status”).innerHTML = ’Completed’ ;

Answer 123

C

Question 124

A developer wants to leverage a module to print a price in pretty format, and has imported a method as shown below:

Import printPrice from ‘/path/PricePrettyPrint.js’;

Based on the code, what must be true about the printPrice function of the PricePrettyPrint module for this import to work ?

A. printPrice must be be a named export
B. printPrice must be an all export
C. printPrice must be the default export
D. printPrice must be a multi exportc

Answer 124

C

Question 125

What are two unique features of functions defined with a fat arrow as compared to normal function definition?

Choose 2 answers

A. The function generated its own this making it useful for separating the function’s scope from its enclosing scope.
B. The function receives an argument that is always in scope, called parentThis, which is the enclosing lexical scope.
C. If the function has a single expression in the function body, the expression will be evaluated and implicit returned.
D. The function uses the this from the enclosing scope.

Answer 125

A,B

Question 126

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 to make this code work as expected?

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.addCallback(“click”, function() {
D. Replace line 02 with button.addEventListener(“onclick”, function() {

Answer 126

A

Question 127

The developer wants to test this code:

Const toNumber =(strOrNum) => strOrNum;

Which two tests are most accurate for this code?

Choose 2 answers

A. console.assert(toNumber(‘2’) === 2);
B. console.assert(Number.isNaN(toNumber()));
C. console.assert(toNumber(‘-3’) < 0);
D. console.assert(toNumber () === NaN);

Answer 127

A,C

Question 128

A developer implements a function that adds a few values.
Function sum(num) {
If (num == undefined) {
Num =0;
}
Return function( num2, num3){
If (num3 === undefined) {
Num3 =0 ;
}
Return num + num2 + num3;
}
}

Which three options can the developer invoke for this function to get a return value of 10?

Choose 2 answers

A. Sum () (20)
B. Sum (5, 5) ()
C. sum() (5, 5)
D. sum(5)(5)
E. sum(10) ()

Answer 128

C,D

Question 129

Refer to the code below: function changeValue(param) {
Param =5;
}
Let a =10;
Let b =5; changeValue(b);
Const result = a+ “ - ”+ b;
What is the value of the result when the code executes?

A. 10 -10
B. 5 -5
C. 5 - 10
D. 10 - 5

Answer 129

A

Question 130

Refer to the following code that performs a basic mathematical operation on a provided input: function calculate(num) {
Return (num +10) / 3;
}
How should line 02 be written to ensure that x evaluates to 6 in the line below? Let x = calculate (8);

A. Return Number((num +10) /3 );
B. Return (Number (num +10 ) / 3;
C. Return Integer(num +10) /3;
D. Return Number(num + 10) / 3;

Answer 130

B

Question 131

Refer to the code below:
Const resolveAfterMilliseconds = (ms) => Promise.resolve ( setTimeout (( => console.log(ms), ms ));
Const aPromise = await resolveAfterMilliseconds(500);
Const bPromise = await resolveAfterMilliseconds(500);
Await aPromise, wait bPromise;

What is the result of running line 05?

A. aPromise and bPromise run sequentially.
B. Neither aPromise or bPromise runs.
C. aPromise and bPromise run in parallel.
D. Only aPromise runs.

Answer 131

B

Question 132

Refer to the code below:
Const searchTest = ‘Yay! Salesforce is amazing!” ;
Let result1 = searchText.search(/sales/i); Let result 21 = searchText.search(/sales/i);
console.log(result1); console.log(result2);
After running this code, which result is displayed on the console?

A. > true > false
B. > 5 >5
C. >5>-1
D. >5>0

Answer 132

B

Question 133

Why would a developer specify a package.jason as a developed forge instead of a dependency ?

A. It is required by the application in production.
B. It is only needed for local development and testing.
C. Other required packages depend on it for development.
D. It should be bundled when the package is published.

Answer 133

B

Question 134

Refer to the code below:
let o = {
get js() {
let city1 = String(“st. Louis”); let city2 = String(“ New York”); return { firstCity: city1.toLowerCase(),
secondCity: city2.toLowerCase(),
}
}
}
What value can a developer expect when referencing o.js.secondCity?

A. Undefined
B. ‘ new york ’
C. ‘ New York ’
D. An error

Answer 134

B

Question 135

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.

Answer 135

B

Question 136

A developer has two ways to write a function:
Option A:
function Monster() { This.growl = () => {
Console.log (“Grr!”);
}
}
Option B:
function Monster() {}; Monster.prototype.growl =() => { console.log(“Grr!”);
}
After deciding on an option, the developer creates 1000 monster objects. How many growl methods are created with Option A Option B?

A. 1 growl method is created for Option A. 1000 growl methods are created for Option
B. 1000 growl method is created for Option A. 1 growl methods are created for Option
C. 1000 growl methods are created regardless of which option is used.
D. 1 growl method is created regardless of which option is used.

Answer 136

B Research

Question 137

Which three browser-specific APIs are available for developers to persist data between page loads?

Choose 3 answers

A. IIFEs
B. indexedDB
C. Global variables
D. Cookies
E. localStorage.

Answer 137

A B E

Question 138

Refer to the code below:
Const myFunction = arr => {
Return arr.reduce((result, current) =>{
Return result = current;
}, 10};
}

What is the output of this function when called with an empty array ?

A. Returns 0
B. Throws an error
C. Returns 10
D. Returns NaN

Answer 138

C

Question 139

In the browser, the window object is often used to assign variables that require the broadest scope in an application Node.js application does not have access to the window object by default.

Which two methods are used to address this?

A. Use the document object instead of the window object.
B. Assign variables to the global object.
C. Create a new window object in the root file.
D. Assign variables to module.exports and require them as needed.

Answer 139

B

Question 140

Refer to the following array:
Let arr = [ 1,2, 3, 4, 5];

Which three options result in x evaluating as [3, 4, 5] ? Choose 3 answers.

A. Let x= arr.filter (( a) => (a<2));
B. Let x= arr.splice(2,3);
C. Let x= arr.slice(2);
D. Let x= arr.filter((a) => ( return a>2 ));
E. Let x = arr.slice(2,3);

Answer 140

B,C,D

Question 141

Refer to code below:
Const objBook = {
Title: ‘Javascript’,
};
Object.preventExtensions(objBook); Const newObjBook = objBook; newObjectBook.author = ‘Robert’;

What are the values of objBook and newObjBook respectively?

A. [title: “javaScript”] [title: “javaScript”]
B. {author: “Robert”, title: “javaScript} Undefined
C. {author: “Robert”, title: “javaScript}
{author: “Robert”, title: “javaScript}
D. {author: “Robert”}
{author: “Robert”, title: “javaScript}

Answer 141

A

Question 142

Refer to code below:

console.log(0);

setTimeout(() => (
console.log(1);
});

console.log(2);

setTimeout(() => {
console.log(3);
), 0);

console.log(4);

In which sequence will the numbers be logged?

A. 01234
B. 02431
C. 02413
D. 13024

Answer 142

C

Question 143

A developer implements and calls the following code when an application state change occurs:
Const onStateChange =innerPageState) => {
window.history.pushState(newPageState, ‘ ’, null);
}
If the back button is clicked after this method is executed, what can a developer expect?

A. A navigate event is fired with a state property that details the previous application state.
B. The page is navigated away from and the previous page in the browser’s history is loaded.
C. The page reloads and all Javascript is reinitialized.
D. A popstate event is fired with a state property that details the application’s last state.

Answer 143

B

Question 144

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);

Answer 144

B

Question 145

A developer wants to define a function log to be used a few times on a single-file JavaScript script.

01 // Line 1 replacement
02 console.log(‘“LOG:’, logInput);
03 }

Which two options can correctly replace line 01 and declare the function for use? Choose 2 answers

A. function leg(logInput) {
B. const log(loginInput) {
C. const log = (logInput) => {
D. function log = (logInput) {

Answer 145

A,C

Question 146

A developer wants to use a module named universalContainersLib and then call functions from it. How should a developer import every function from the module and then call the functions foo and bar?

A. import * from ‘/path/universalContainersLib.js’;
universalContainersLib. foo ()7 universalContainersLib.bar ();
B. import {foo,bar} from ‘/path/universalCcontainersLib.js’; foo(): bar()?
C. import all from ‘/path/universalContainersLib.js’;
universalContainersLib.foo(); universalContainersLib.bar ();
D. import * as lib from ‘/path/universalContainersLib.js’; lib.foo(); lib. bar ();

Answer 146

D

Question 147

Which two console logs output NaN?
Choose 2 answers | |

A. console.log(10 / Number(‘5) ) ;
B. console.log(parseInt ‘ (“two’)) ;
C. console.log(10 / 0);
D. console.loeg(10 / ‘five’);

Answer 147

B D

Question 148

A developer wants to use a try…catch statement to catch any error that countSheep () may throw and pass it to a handleError () function.

What is the correct implementation of the try…catch?

A.
Try{
setTimeout(function(){
countsheep();
), 1000);
}catch(e){
handleError(e);
}

B.

try{
countsheep();
}finally{
handleError(e);
}

C.
setTimeout(function(){
try{
countsheep();
}catch(e){
handleError(e);
}
),1000);

D.
try{
countsheep();
}handleError(e){
carch(e);
}

Answer 148

A

Question 149

A developer has a formatName function that takes two arguments, firstName and lastName and returns a string. They want to schedule the function to run once after five seconds.
What is the correct syntax to schedule this function?

A. setTimeout (formatName(), 5000, “John”, “BDoe”);
B. setTimeout (formatName(‘John’, ‘’Doe’), 5000);
C. setTimout(() => { formatName(“John’, ‘Doe’) }, 5000);
D. setTimeout (‘formatName’, 5000, ‘John”, “Doe’);

Answer 149

D

Question 150

Which statement parses successfully?

A. JSON.parse(‘ “foo” ’);
B. JSON.parse ( “foo” );
C. JSON.parse( “ ‘foo’ ” );
D. JSON.parse ( ‘foo’ );

Answer 150

A

Question 151

Given the following code:

let x = null

console.log(typeof x);

is the output of line 02?
A. ‘‘x’’
B. ‘‘null’’’
C. ‘‘object’’
D. ‘‘undefined’’

Answer 151

C

Question 152

A test has a dependency on database. query. During the test, the dependency is replaced with an object called database with the method,
Calculator query, that returns an array. The developer does not need to verify how many times the method has been called.
Which two test approaches describe the requirement? Choose 2 answers

A. White box
B. Stubbing
C. Black box
D. Substitution

Answer 152

A,D

Question 153

Universal Containers (UC) just launched a new landing page, but users complain that the website is slow. A developer found some functions any that might cause this problem. To verify this, the developer decides to execute everything and log the time each of these three suspicious functions consumes.

console.time(‘Performance’);
maybeAHeavyThing();
thisCouldTakeTooLong();
orMaybeThisOne();
console.endTime(‘Performance’);

Which function can the developer use to obtain the time spent by every one of the three functions?

A. console.timeLog ()
B. console.timeStamp ()
C. console.trace()
D. console.getTime ()

Answer 153

A

Question 154

A developer wrote the following code to test a sum3 function that takes in an array of numbers and returns the sum of the first three numbers in the array, and the test passes.

A different developer made changes to the behavior of sum3 to instead sum only the first two numbers present in the array.

let res = sum3([1,4,1]);
console.assert(res === 6);

let res = sum3([1,5,0,5]);
console.assert(res === 6);

Which two results occur when running this test on the updated sum3 function? Choose 2 answers

A. The line 05 assertion passes.
B. The line 02 assertion passes.
C. The line 02 assertion fails.
D. The line 05 assertion fails.

Answer 154

B,D

Question 155

A developer has a web server running with Node.js. The command to start the web server is node server.js. The web server started having latency issues. Instead of a one-second turnaround for web requests, the developer now sees a five-second turnaround.

Which command can the web developer run to see what the module is doing during the latency period?

A. NODE_DEBUG=true node server.js
B. DEBUG=http, https node server.js
C. NODE_DEBUG=http,https node server.js
D. DEBUG=true node server.js

Answer 155

D

Question 156

function changeValue(param){
param = 5;
}
let a = 10;
let b = a;

changeValue(b);

const result = a + ‘ - ‘ + b;

What is the value of the result when the code executes?
A. 10-10
B. 5-5
C. 10-5
D. 5-10

Answer 156

A

Question 157

developer uses the code below to format a date.

const date = new Date(220,05,10);
const dateTimeDisplayOption = {
year: ‘numeric’,
month: ‘long’,
day: ‘numeric’
};

const formtattedDate = date.toLocaleDateString(‘en’, dateTimeDisplayOption);

After executing, what is the value of formattedDate?

A. May 10, 2020
B. June 10, 2020
C. October 05, 2020
D. November 05, 2020

Answer 157

B

Question 158

Refer of the string below:
Const str = ‘salesforce’;

Which two statement result in the word ‘Sale’? Choose 2 answers

A. str, substring (0,5) ;
B. str, substr(0,5) ;
C. str, substring(1,5) ;
D. str, substr(1,5) ;

Answer 158

A,B

Question 159

A developer writes the code below to return a message to a user attempting to register a new username. If the username is available, a variable named nag is declared and assigned a value on line 03.

Function getAvailabilityMessage(item) {
If (getAvailability(item)){
Var msg =”Username available”;
}
Return msg;
}

What is the value of msg when getAvailableabilityMessage (“newUserName”) is executed and get Availability (“newUserName”) returns true?

A. “msg is not defined”
B. “newUserName”
C. “Username available”
D. undefined

Answer 159

C

Question 160

myArraym can have one level, two levels, or more levels.
Which statement flattens myArray when it can be arbitrarily nested?

A. myArray. reduce ((prev, curr) => prev.concat(curr) [ ]);
B. myArray. join (“,”). split (“,”);
C. [ ] .concat {. . .myArray) ;
D. myArray.flat(Infinity);

Answer 160

A

Question 161

Refer to the following code:

let obj = {
foo: 1,
bar: 2
}

let output = [];

for(let something in obj){
output.push(something);
}

console.log(output);

What is the output of line 11?

A. [1,2]
B. [“bar”, “foo”]
C. [“foo:1”, “bar:2”]
D. [“foo”, “bar”]

Answer 161

D

Question 162

Considering the implications of ‘use strict’ on line 04, which three statements describe the execution of the code?

x=3.14;
function myfunction() {
‘use strict’;
y=x;
}
z=x;
myFunction();

Choose 3 answers

A. z is equal to 3.14.
B. ‘use strict’ is hoisted, so it has an effect on all lines.
C. ‘use strict’ has an effect only on line 05.
D. ‘use strict’ has an effect between line 04 and the end of the file.
E. Line 05 throws an error.

Answer 162

A,C,E

Question 163

Which statement can a developer apply to increment the browser’s navigation history without a page refresh?

A. window.history.pushState(newStateObject);
B. window.history.pushStare(newStateObject, ‘ ‘, null);
C. window.history.replaceState(newStateObject,’ ‘, null);
D. window.history.state.push(newStateObject);

Answer 163

C

Question 164

What is the console output?

class student {
constructor(name) {
this.name = name;
}

takeTest() {
console.log(‘$(this.name ) got 70% on test)
}
}

class BetterStudent extends Student {
constructor(name){
super(name);
this.name = ‘Better Student ‘ + name;
}

takeTest() {
console.log(‘$(this.name) got 100% on test);
}
}

let student = new BetterStudent(Jackie);

student.TakeTest();

A. > Better student Jackie got 70% on test.
B. > Jackie got 70% on test.
C. > Uncaught Reference Error
D. > Better student Jackie got 100% on test.

Answer 164

D

Question 165

Considering that JavaScript is single-threaded, what is the output of line 08 after the code executes?

let total = 10;

const interval = setInterval(() => {
total++;
clearInterval(interval);
total++;
},0);
total++;

console.log(total);

A. 10
B. 11
C. 12
D. 13

Answer 165

B

Question 166

Given the code below:

function Person(name, email) {
this.name = name;
this.email = email;
}

const john = new Person (John, john@email.com’);
const jane = new Person (Jane, jane@email.com’);
const emily = new Person (Emily, emily@email.com’);

let userList = [john, jane, emily];

Which method can be used to provide a visual representation of the list of users and to allow sorting by the name
or email attribute?

A . console.group(usersList) ;
B . console.table(usersList) ;
C . console.info(usersList) ;
D . console.groupCol lapsed (usersList) ;

Answer 166

A

Question 167

Which value can a developer expect when referencing country, capital, and cityString?

let country = {
get capitol () {
let city = Number(“London”);

return {
cityString: city.toString(),
}
}
}

A. ‘London’
B. undefined
C. An error
D. ‘NaN’

Answer 167

D

Question 168

Refer to the code below:

function Person(){
this.firstname = ‘John’;
}

person.prototype = {
job: x => ‘Developer’;
}

const myFather = new Person();
const. result = myFather.firstName + ‘ ‘ + myFather.job();

What is the value of result after line 10 executes?

A. Error: myFather.job is not a function
B. John Developer
C. undefined Developer
D. John undefined

Answer 168

B

Question 169

Which two options are core Node.js modules?

Choose 2 answers

A. worker
B. isotream
C. exception
D. http

Answer 169

B,D

Question 170

A developer is trying to handle an error within a function.

Which code segment shows the correct approach to handle an error without propagating it elsewhere?

A.
try{
doSomething();
}catch (error){
return error;
}

B.

try{
doSomething();
}catch (error){
return null;
}

C.
try{
doSomething();
}catch (error){
throw new Error(‘Error found’);
}

D.
try{
doSomething();
}catch (error){
processError(error);
}

Answer 170

D

Question 171

bar, awesome is a popular JavaScript module. the versions publish to npm are:
1.2
1.3.1
1.3.5
1.4.0

Teams at Universal Containers use this module in a number of projects. A particular project has the package, json
definition below.

{
“name”: “UC Project Extra”;
“version”: “0.0.5”
“dependencies”: {
“bar.awesome”: “~1.3.0”
}
}

A developer runs this command: npm install.
Which version of bar .awesome is installed?
A . 1.3.1
B . 1.3.5
C . The command fails, because version 130 is not found
D . 1.4.0

Answer 171

B

Question 172

Given the expressions var1 and var2, what are two valid ways to return the concatenation of the two expressions and ensure it is string? Choose 2 answers

A. var1 + var2
B. var1.toString( ) + var2.toString( )
C. String(var1).concat (var2)
D. string.concat(var1 +var2)

Answer 172

B C

Question 173

A developer needs to debug a Node.js web server because a runtime error keeps occurring at one of the endpoints.
The developer wants to test the endpoint on a local machine and make the request against a local server to look at the behavior. In the source code, the server, js file will start the server. the developer wants to debug the Node.js server only using the terminal.
Which command can the developer use to open the CLI debugger in their current terminal window?

A. node -i server.js
B. node inspect server.js
C. node server.js inspect
D. node start inspect server.js

Answer 173

B

Question 174

Refer to the following object.

01 const dog = {
02 firstName: ‘Beau’,
03 lastName: ‘Boo’,
04 get fullName() {
05 return this.firstName + ‘ ‘ + this.LastName;
06 }
07 );

How can a developer access the fullName property for dog?
A . Dog.fullName
B . Dog.fullName( )
C . Dog, get, fullName
D . Dog, function, fullName

Answer 174

A

Question 175

Given the following code:

01 counter = 0
02 const logCounter = () => (
03. console.log(counter);
04 );
05 logCounter();
06 setTimeout(logCounter, 2100);
07 setInterval(() => {
08 counter ++
09 logCounter();
10 ), 1000);

What will be the first four numbers logged?
A . 0012
B . 0112
C . 0122
D . 0123

Answer 175

C

Question 176

There is a new requirement for a developer to implement a currPrice method that will return the current price of
the item or sales..

01 let regItem = new item(scarf , 50);
02 let salesItem = new SalesItem(shirt, 80, .1);
03 Item.protoType.currPrice = function() { return this.price }
04 console.log(regItem.currPrice());
05 console.log(saleItem.currPrice());
06
07 Saleitem.protoType.currPrice = function() { return this.price = this.price * this. discount}
08 console.log(regItem.currPrice());
09 console.log(saleItem.currPrice());

What is the output when executing the code above
A . 50
Uncaught TypeError: saleItem,desrcription is not a function
50
80

B . 50
80
50
72

C . 50
80
72

D . 50
80
Uncaught Reference Error:this,discount is undefined
72

Answer 176

B

Question 177

A developer copied a JavaScript object:

function person(){
this.firstName = ‘John’;
this.LastName = ‘Doe’;

this.name = () => ‘${this.firstName},${this.LastName};
}

const john = new person();
const dan = object.assign(john);
dan.FirstName = ‘Dan;

How does the developer access dan’s forstName,lastName? Choose 2 answers

A . dan.name
B . dan.firstname( ) + dan.lastName ( )
C . dan.firstName + dan.Lastname
D . dan.name( )

Answer 177

C,D

Question 178

A developer is setting up a Node,js server and is creating a script at the root of the source code, index,js, that will start the server when executed. The developer declares a variable that needs the folder location that the code executes from. Which global variable can be used in the script?

A. window.location
B. _filename
C. _dirname
D. this.path

Answer 178

B

Question 179

A developer at Universal Containers is creating their new landing page based on HTML, CSS, and JavaScript. The website includes multiple external resources that are loaded when the page is opened.
To ensure that visitors have a good experience, a script named personalizeWebsiteContent needs to be executed when the webpage Is loaded and there Is no need to wait for the resources to be available.
Which statement should be used to call personalizeWebsiteContent based on the above business requirement?

A. windows,addEventListener(‘load’, personalizeWebsiteContent);
B. windows,addEventListener(‘DOMContent Loaded ‘, personalizeWebsiteContent);
C. windows,addEventListener(‘onload’, personalizeWebsiteContent);
D. windows,addEventListener(‘onDOMCContentLoaded’, personalizeWebsiteContent);

Answer 179

A

Question 180

const myFunction = arr => {
return arr.reduce((result, current) => {
return result + current;
},5);
}

What is the output of this function when called with an empty array?

A. Return 0
B. Return 5
C. Return NaN
D. Return Infinity

Answer 180

B

Question 181

class Ship{
constructor(size) {
this.size = size;
}
}

class FinishingBoat extends ship {
constructor(size, capacity) {
// missing code
this.capacity = capacity;
}

displyaycapacity(){
console.log(‘This boat has a capacity of $(this.capacity) people);
}
}
let myBoat = new FinishingBoat (‘medium’ 10 );
myBoat.displayCapacity();

Which statement should be added to line 09 for the code to display ‘The boat has a capacity of 10 people?

A. super.size = size;
B. ship.size size;
C. super(size);
D. this.size = size;

Answer 181

D

Question 182

Let arr = [1, 2, 3, 4, 5];
Which three options result in x evaluating as [1, 2]? Choose 3 answer

A. let x = arr. slice (2);
B. let x = arr. slice (0, 2);
C. let x arr.filter((a) => (return a <= 2 });
D. let x = arr.filter ((a) => 2 }) ;
E. let x =arr.splice(0, 2);

Answer 182

B,C,E

Question 183

Refertothefollowingcode:
Let obj ={
Foo: 1,
Bar: 2
}
Let output =[],
for(let something of obj{
output.push(something);
}
console.log(output);

What is the output line 11?

A. [1, 2]
B. [‘’foo’’, ‘’bar’’]
C. [‘’foo’’:1, ‘’bar’’:2’’]
D. An error will occur due to the incorrect usage of the for…of statement on line 07.

Answer 183

D

Question 184

let str1 = ‘Java’;
let str2 = ‘Script’;

Which three expressions return the string JavaScript? Choose 3 answers

A. Str1.join (str2);
B. Str1.concat (str2);
C. Concat (str1, str2);
D. $(str1) $ (str2} ‘;
E. Str1 + str2;

Answer 184

B,D,E

Question 185

A developer has the following array of hourly wages:
Let arr = (8, 5, 9, 75, 11, 25, 7, 75, , 13, 25);
For workers making less than $10 an hour rate should be multiple by 1.25 and returned in a new array.
How should the developer implement the request?

A. let arrl = arr.filter((val) => val < 10).map((num) -> num = 1.25);
B. let arrl = arr .rr.acArray ((val) => ( val < 10 )) ,map((num) => { num * 1.25 ));
C. let arrl = arr-map((num) => { return ran * 1.25 }).filter((val) -> { return val < 10));
D. let arrl = arr.filterBy((val) => val < 10 ).aapBy<(num) -> num = ..25 );

Answer 185

C

Question 186

A developer wants to create an object from a function in the browser using the code below.

Function Monster() { this.name = ‘hello’ };
Const m = Monster();

What happens due to the lack of the mm keyword on line 02?

A. window.name is assigned to ‘hello’ and the variable = remains undefined.
B. window.m Is assigned the correct object.
C. The m variable is assigned the correct object but this.name remains undefined.
D. The m variable is assigned the correct object.

Answer 186

A

Question 187

Given the following code, what is the value of x? let x = ‘15’ + (10 * 2);

A. 35
B. 50
C. 1520
D. 3020

Answer 187

C

Question 188

Given the code below:
Which three code segments result in a correct conversion from number to string? Choose 3 answers

A. let strValue = numValue. toString();
B. let strValue = * * 4 numValue;
C. let strValue = numValue.toText ();
D. let scrValue = String(numValue);
E. let strValue = (String)numValue;

Answer 188

A,B,D

Question 189

01 setTimeout (() => {
02 console.log(1);
03 ),1100);
04 console.log(2);
05 new Promise ((resolve, reject) => {
06 setTimeout (() => {
07 console.log(3);
08 },1000);
09}}.catch(() => {
10 console.log(4);
11 });
12 console.log(5);

What is logged to the console?

A. 1 2 3 4 5
B. 1 2 5 3 4
C. 2 5 1 3 4
D. 2 5 3 4 1

Answer 189

D

Question 190

//<div>
// <div id ="row-uc">Univeral Containers</div>
// <div id ="row-as">Applied Shipping</div>
// <div id ="row-bt">Burlington Textiles</div>
//</div>

Which statement adds the priority-account CSS class to the Universal Containers row?

A. document.querySelector (#row-uc’).classes-push(‘priority-account’);
B. document.getElementByid(‘row-uc’).addClass(‘priority-account*);
C. document.querySelectorAll(‘#row-uc’).classList.add(“priority-accour’);
D. document.queryselector(‘#row-uc’).classList.add(‘priority-account’);

Answer 190

D

Question 191

A developer is leading the creation of a new web server for their team that will fulfill API requests from an existing client.
The team wants a web server that runs on Node.Js, and they want to use the new web framework Minimalist.Js. The lead developer wants to advocate for a more seasoned back-end framework that already has a community around it.
Which two frameworks could the lead developer advocate for? Choose 2 answers

A. Gatsby
B. Angular
C. Express
D. Koa

Answer 191

B,C

Question 192

Refer to the string below: const str = ‘Salesforce’;
Which two statements result in the word ‘Sales’? Choose 2 answers

A. str.substr(1, 5);
B. str.substr (0, 5);
C. str.substring (1, 5);
D. str.substring (0, 5);

Answer 192

B,D

Question 193

Given the JavaScript below:

01 function filterDOM(searchString){
02 const parsedSearchString = searchsting && searchsting.toLowerCase();
03 document.querySelectorAll(‘.account’).forEach(account => {
04 const accountName = account.innerHTML.toLowerCase();
05 account.style.backgroundColor = accountName.include(parseSearchString) ? //InsertCodeHere//
06 });
07 }

Which code should replace the placeholder comment on line 05 to highlight accounts that match the search string’

A. ‘yellow’ : null
B. null : ‘yellow’
C. ‘none1 : “yellow’
D. ‘yellow : ‘none’

Answer 193

D

Question 194

Which two statement could be inserted at line 17 to enable the function call on line 18? Choose 2 answers

01 function Tiger(){
02 this.Type = ‘Cat’;
03 this.size = ‘large’;
04 }
05
06 let tony = new Tiger();
07 tony.roar = () =>{
08 console.log(‘They’re great1’);
09 };
10
11 function Lion(){
12 this.type = ‘Cat’;
13 this.size = ‘large’;
14 }
15
16 let leo = new Lion();
17 //Insert code here
18 leo.roar();

A. Object.assign (leo, tony);
B. Object.assign (leo. Tiger);
C. leo.roar = () => { console.log(‘They're pretty good!’); );
D. leo.prototype.roar = ( ) =>( console.log(‘They're pretty good!’); };

Answer 194

A,C

Question 195

//<html lang=’‘en’’>
//<table onclick=’‘console.log(Table log’);’’>
//<tr id=’‘row1’’>
//<td>Click me!</td>
//</tr>
//<table>
//

function printMessage(event) {
console.log('Row log');
event.stopPropagnation();
}
Let elem = document.getElementById('row1');
elem.addEventListener('click', printMessage, false);
//

//</html>

Which code change should be done for the console to log the following when ‘Click me!’ is clicked’ > Row log
> Table log

A. Remove lines 13 and 14
B. Change line 10 to event.stopPropagation (false) ;
C. Change line 14 to elem.addEventListener (‘click’, printMessage, true);
D. Remove line 10

Answer 195

B

Question 196

A developer has an ErrorHandler module that contains multiple functions.
What kind of export should be leveraged so that multiple functions can be used?

A. all
B. named
C. multi
D. default

Answer 196

B

Question 197

function Animal (size, type) {

this.size = size || ‘small’;
this.type = type || ‘Animal’;
this.cantalk = false;
}

let pet = function (size, type, name, owner){
Animal.call(this, size, type);

this.name = name;
this.owner = owner;

pet prototype = object.create(Animal.prototype);
let pet1 = new Pet();

console.log(pet1);

Given the code above, which three properties are set for pet1? Choose 3 answers

A. name
B. owner
C. type
D. canTalk
E. size

Answer 197

C,D,E

Question 198

//<div id='main'>
//<ul>
//<li>Leo</li>
//<li>Tony</li>
//<li>Tiger</li>
//</ul>
//</div>

Which JavaScript statement results in changing “ The Lion.”?

A. document.querySelectorAll(‘$main $TONY’).innerHTML = ’“ The Lion
B. document.querySelector(‘$main li:second-child’).innerHTML = “ The Lion ’;
C. document.querySelector(‘$main li.Tony’).innerHTML = ’“ The Lion ’;
D. document.querySelector(‘$main li:nth-child(2)’),innerHTML = “ The Lion. ’;

Answer 198

A

Question 199

Refer to the code below:
01 document.body.addEventListner(‘click’,(event)=>{
02 if(//Answer Goes here//){
03 console.log(‘myElement clicked);
04 }
05 });

Which replacement for the conditional statement on line 02 allows a developer to correctly determine
that a specific element, myElement on the page had been clicked?
A. event.target.id ==’myElement’
B. event.target ==’myElemnt’
C. event
D. target.id == ‘myElement’

Answer 199

A

Question 200

Given the following code:

let x = null;
console.log(typeof x);

What is the output?

A. “object”
B. “undefined”
C. “null”
D. “x”

Answer 200

A

Question 201

A developer writes the code below to calculate the factorial of a given number function

sum(number){
return number * sum(number-1);
}
sum(3);

what is the result of executing the code.

A. 0
B. 6
C. Error
D. -Infinity

Answer 201

C

Question 202

At Universal Containers, every team has its own way of copying JavaScript objects. The code snippet shows an Implementation from one team:

Function Person() {
this.firstName = ‘‘John’’;
this.lastName = ‘Doe’;
This.name =() => (
console.log(‘Hello $(this.firstName) $(this.firstName)’);
)}

Const john = new Person ();
Const dan = JSON.parse(JSON.stringify(john));
dan.firstName =’Dan’;
dan.name();

What is the output of the code execution?

A. Hello John Doe
B. Hello Dan
C. Hello Dan Doe
D. SyntaxError: Unexpected token in JSON

Answer 202

D

Question 203

Refer to the code below
let inArray = [[1,2],[3,4,5]];

which two statements results in the array [1,2,3,4,5]?

choose 2 answer

A. [ ].concat(…inArray);
B. [ ].concat.apply(inArray,[ ]);
C. [ ].concat([…inArray])
D. [ ].concat.apply([ ],inArray);

Answer 203

A,D

Question 204

A developer has two ways to write a function:

Option A:
function Monster(){ this.growl = ()=>{
console.log(‘Grr!’);
}
}

Option B:
function Monster(){}; Monster.prototype.growl = ()=>{ console.log(‘Grr!’);
}

After deciding on an option, the developer creates 1000 monster objects. How many growl methods are created with Option A and Option B?

A. 1000 for Option A, 1 for Option B
B. 1 methods for both
C. 1000 for both
D. 1 for Option A, 1000 for Option B

Answer 204

A

Question 205

Refer to the following code:
class Vehicle{ constructor(plate){
this.plate = plate;
}
}
class Truck extends Vehicle{
constructor(plate, weight){
//Missing code
this.weight = weight;
}
displayWeight(){
console.log(The truck ${this.plate} has a weight of ${this.weight}lb.);
}
}let myTruck = new Truck(‘123Ab’,5000);
myTruck.displayWeight();
Which statement should be added to missing code for the code to display ‘The truck 123AB has a weight of 5000lb.

A. super(plate)
B. super.plate = plate
C. Vehicle.plate = plate
D. this.plate = plate

Answer 205

A

Question 206

Refer to the code below:

const car = { price:100, getPrice:function(){
return this.price;
} };

const customCar = Object.create(car);
customCar.price = 70;

delete customCar.price;

const result = customCar.getPrice();

What is the value of result after the code executes?

A. 100
B. undefined
C. null
D. 70

Answer 206

A

Question 207

Refer to following code block:

Let array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,];
Let output =0;

For (let num of array){
if (output >10){
Break;
}

if(num % 2 == 0){
Continue;
}

Output +=num;

What is the value of output after the code executes?
A . 16
B . 36
C . 11
D . 25

Answer 207

A

Question 208

Refer to the code below:

01 let total = 10;
02 const interval = setInterval (() => {
03 total ++;
04 clearInterval (interval);
05 total++;
0+ ),0);
07 total ++;
08 console.log(total);

Considering that JavaScript is single-threaded, what is the output of line 08 after the code executes?
A . 10
B . 11
C . 12
D . 13

Answer 208

B

Question 209

Given the code below:

const delay = async delay =>{
return new Promise((resolve,reject)=>{
console.log(1);
setTimeout(resolve,deleay);
});
};
const callDelay = async ()=>{
console.log(2);
const yup = await delay(1000);
console.log(3);
}
console.log(4);
callDelay();
console.log(5);

What is logged to the console?

A . 4 2 1 5 3
B . 4 2 1 5 6
C. 4 5 1 2 3
D. 4 5 2 3 1

Answer 209

A

Question 210

Refer to the following code block:
class Animal{
constructor(name){
this.name = name;
}
makeSound(){
console.log(${this.name} is making a sound.)
}
}
class Dog extends Animal{
constructor(name){
super(name)
this.name = name;
}
makeSound(){
console.log(${this.name} is barking.)
}
}
let myDog = new Dog(‘Puppy’);
myDog.makeSound();

What is the console output?

A . Puppy is barking
B . Puppy is cracking
C. Puppy is making a sound
D. Undefined

Answer 210

A

Question 211

A developer has an is Dog function that takes one argument cat. They want to schedule the function to run every
minute.

What is the correct syntax for scheduling this function?

A developer has an is Dog function that takes one argument cat. They want to schedule the function to run every
minute.
What is the correct syntax for scheduling this function?

A . setInterval(isDog, 60000,’cat’);
B . setInterval(isDog, 50000,’cat’);
C . setTimeout(isDog, 60000,’cat’);
D . setTimeout(isDog, 50000,’cat’);

Answer 211

A

Question 212

A developer wants to use a module called DataPrettyPrint. This module exports one default function called
printDate ().
How can a developer import and use the printDate() function?

A. import DataPrettyPrint from ‘/path/DataPrettyPrint.js’/
DataPrettyPrint.printDate();

B. import printDate from ‘/path/DataPrettyPrint.js’/
printDate();

C. import printDate from ‘/path/DataPrettyPrint.js’/
DataPrettyPrint.printDate();

D. import DataPrettyPrint() from ‘/path/DataPrettyPrint.js’/
printDate();

Answer 212

B

Question 213

Given the following code:

01 counter = 0
02 const logCounter = () => (
03. console.log(counter);
04 );
05 logCounter();
06 setTimeout(logCounter, 2100);
07 setInterval(() => {
08 counter ++
09 logCounter();
10 ), 1000);

What will be the first four numbers logged?
A . 0012
B . 0112
C . 0122
D . 0123

Answer 213

C