Salesforce Certified JavaScript Developer (JS-Dev-101) Exam Practice Test Instant Access

Question 1

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 teamhas already built using HTML, CSS, and

JavaScript.

Which three benefits of Node.js can the developer use to persuade their manager?

Choose 3 answers:

AInstalls with its own package manager to install and manage third-party libraries.

BEnsures stabilitywith one major release every few years.

CPerforms a static analysis on code before execution to look for runtime errors.

DExecutes server-side JavaScript code to avoid learning a new language.

EUses non-blocking functionality for performant requesthandling .

Answer : A, C, E

Question 2

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?

AReferenceError: eyeColor is not defined

BReferenceError: assignment to undeclared variable ''Person''

CDeveloper

DUndefined

Answer : D

Question 3

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 thedeveloper has, which code logs an error at boost

with an event?

AServer.catch ((server) => {console.log('ERROR', error);});

BServer.error ((server) => {console.log('ERROR', error);});

CServer.on ('error', (error) => {console.log('ERROR', error);});

DTry{server.start();} catch(error) {console.log('ERROR', error);}

Answer : C

Question 4

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

True + '13' + NaN

A' 113Nan '

B14

C' true13 '

D' true13NaN '

Answer : D

Question 5

A developer at Universal Containers is creating their new landing page based on HTML, CSS, and JavaScript.

To ensure that visitors have a good experience, a script named personalizeWebsiteContent needs to be executed when the webpage is fully loaded (HTML content and all related files), in order to do some custom initializations.

Which implementation should be used to call Fe:s:-a;::eHec5;te::.-.ter.: based on the business requirement above?

AAdd a listener to thewindow object to handle the DOMContentLoaded event

BAdd a handler to the personalizeWebsiteContent script to handle the load event

CAdd a listener to the window object to handle the lead event

DAdd a handler to the personalizeWebsiteContent script tohandle the DOMContentLoaded event

Answer : C

Question 6

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

Choose 3 answers

Ax => ( console.log(' executed ') ; )

B[ ] => ( console.log(' executed ') ;)

C( ) => ( console.log(' executed ') ;)

DX,y,z => ( console.log(' executed ') ;)

E(x,y,z) => ( console.log(' executed ') ;)

Answer : A, E

Question 7

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:

AIf there is an existing setTimeout and the search string change, allow the existingsetTimeout to finish, and do not enqueue a new setTimeout.

BWhen thesearch string changes, enqueue the request within a setTimeout.

CEnsure that the network request has the property debounce set to true.

DIf there is an existing setTimeout and the search string changes, cancel the existingsetTimeout using thepersisted timerId and replace it with a new setTimeout.

EStore the timeId of the setTimeout last enqueued by the search string change handle.

Answer : A, B, C