Free Salesforce JS-Dev-101 Exam Questions

Become Salesforce Certified with updated JS-Dev-101 exam questions and correct answers

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Total 217 Questions | Updated On: Oct 24, 2026

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Question 1

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 havinglatency 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: D

Question 2

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: A,C,D

Question 3

Refer to the code below:Which value can a developer expect when referencing country,capital,cityString?

A : 'London'

B : undefined

C : An error

D : 'NaN'

Answer: D

Question 4

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 serverWill 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: C

Question 5

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

Page: 1 / 44

Total 217 Questions | Updated On: Oct 24, 2026

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