| Exam Code | Javascript-Developer-I |
| Exam Name | Salesforce Certified JavaScript Developer (JS-Dev-101) |
| Questions | 147 Questions Answers With Explanation |
| Update Date | July 16,2026 |
| Price |
Was : |
In the evolving cloud development ecosystem, raw programming skill remains the ultimate differentiator for technical professionals. Within the Salesforce landscape, mastering vanilla JavaScript is no longer optional—it is the bedrock required to architect fluid user experiences using modern Lightning Web Components (LWC). Earning your Salesforce Certified JavaScript Developer I credential validates your programmatic fluency, proving you can write efficient, secure, and modern script logic that stands up to enterprise demands.
To navigate this highly technical assessment successfully, you need preparation assets that mirror the actual testing logic. This comprehensive, organically crafted study guide walks you through the core infrastructure of the 2026 Javascript-Developer-I exam, mapping out its blueprint, structural mechanics, and the premium preparation materials provided by Pass4surexams to secure your passing score on the first try.
Studying from dry product documentation can sometimes leave you unprepared for the specific ways exam questions are worded. Incorporating premium 2026 Javascript-Developer-I Exam Dumps into your study routine solves this problem by accurately reflecting the actual testing environment.
Pass4surexams provides highly vetted, organically written Practice Questions and Practice Tests mapped to current 2026 standards. These exam questios compile actual exam layouts with verified answers, ensuring you grasp the underlying logic instead of relying on simple memorization. Incorporating this real exam material into your study schedule gives you an accurate view of how questions are built, helping you pass confidently on your very first try.
The Salesforce Certified JavaScript Developer I evaluation targets engineers who routinely write JavaScript code across the web application stack. Unlike traditional Salesforce certifications that focus heavily on point-and-click administration or proprietary languages like Apex, this credential specifically isolates your proficiency in core web standards.
The test measures your capability to write functional scripting logic, handle asynchronous events, debug faulty execution pipelines, manage browser-specific memory scopes, and execute modern ECMAScript object structures. By passing this exam, you signal to technical managers, development teams, and global clients that you have the capability to design highly reliable, standards-compliant user interfaces without relying on boilerplate code patterns.
Succeeding on exam day requires knowing exactly what kind of test environment you will step into. Reviewing the exact structural boundaries helps you plan your study time efficiently:
| Exam Attribute | Details and Specifications |
|---|---|
| Official Exam Name | Salesforce Certified JavaScript Developer I |
| Official Exam Code | Javascript-Developer-I |
| Questions Architecture | 60 Multiple-Choice or Multiple-Select items |
| Testing Duration | 105 Minutes total |
| Passing Benchmark | 65% minimum correct score |
| Testing Channels | Online proctored session via Webassessor or physically at an authorized center |
| Language Base | English |
This certification path is tailor-made for front-end developers, full-stack programmers, and existing cloud professionals who are stepping directly into framework-driven UI engineering.
Target Audience Profile:
Recommended Prerequisites:
While there are no mandatory testing blockers that prevent you from registering for this multiple-choice exam, candidates typically achieve the best results when they bring:
Note on full certification: To earn the complete "Salesforce Certified JavaScript Developer I" designation, you must pass this multiple-choice exam and complete the Lightning Web Components Specialist Superbadge via Trailhead. You can complete these two steps in any order you choose.
The test blueprint distributes questions systematically across several core pillars of the language. Prioritize your study schedule according to these official syllabus weight percentages:
Variables, Types, and Collections (23%)
Objects, Functions, and Classes (25%)
Browser and Events (17%)
Asynchronous Programming (13%)
Server-Side JavaScript (8%)
Testing, Debugging, and Error Handling (14%)
Earning this credential significantly boosts your credibility and opens doors to new opportunities across the IT industry. Key benefits include:
Our dual-format study pack combines flexible learning with real-world testing simulation to maximize your exam success.
Use the PDF file to read through the questions and master the underlying technical concepts, then switch to the Interactive Practice Test Engine to build real-world stamina under strict timed constraints!
Here are the top questions candidates search for on Google regarding this certification exam:
Q: What is the official cost of the JavaScript Developer I certification exam?
A: The standard registration fee for the Salesforce JavaScript Developer I multiple-choice exam is $200 USD, plus any applicable local taxes. If you need to retake the test, Salesforce applies a standard retake fee of $100 USD. Preparing thoroughly with verified practice materials helps ensure you pass on your first attempt and avoid extra costs.
Q: Do I need to know Apex syntax to pass this multiple-choice exam?
A: No. The JavaScript Developer I multiple-choice exam focuses entirely on platform-agnostic web development. It tests vanilla JavaScript standards (ECMAScript 6+), browser mechanics, and basic Node.js execution. You do not need any knowledge of Apex or Salesforce administration to pass this specific test.
Q: Why do many developers find this specific exam more difficult than standard cloud certifications?
A: Unlike traditional certifications that test your knowledge of platform settings and features, this exam requires you to read and analyze raw code blocks under a time limit. You must evaluate code snippets, identify intentional scoping traps, trace asynchronous execution paths, and determine the exact output of various script fragments.
Q: How long does it take to prepare for this test using Pass4surexams practice materials?
A: Most candidates who dedicate a few hours each day to studying our PDF questions and utilizing the practice test engine report feeling completely prepared to pass the official exam within 1 to 2 weeks.
We are fully committed to helping you achieve your professional goals. To give you complete peace of mind, Pass4surexams provides these premium safeguards for all candidates:
A developer wants to define a function log to be used a few times on a single-fileJavaScript script.01 // Line 1 replacement02 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) {
A developer wants to create an object from a function in the browser using the codebelow:Function Monster() { this.name =‘hello’ };Const z = Monster();What happens due to 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.
A developer uses a parsed JSON string to work with userinformation as in the block below:01 const userInformation ={02 “ id ” : “user-01”,03 “email” : “[email protected]”,04 “age” : 25Which 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)
Considering type coercion, what does the following expression evaluate to?True + ‘13’ + NaN
A. ‘ 113Nan ’
B. 14
C. ‘ true13 ’
D. ‘ true13NaN ’
A developer creates a class that represents a blog post based on the requirement that aPost should have a body author and view count.The Code shown Below:ClassPost {// Insert code hereThis.body =bodyThis.author = author;this.viewCount = viewCount;}}Which statement should be inserted in the placeholder on line 02 to allow for a variable tobe setto a new instanceof 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() {
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’]
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 canbecome fulfilled, settled, or rejected.
A developer creates an object where its properties should be immutable and preventproperties from being added or modified.Which method shouldbe used to execute this business requirement ?
A. Object.const()
B. Object.eval()
C. Object.lock()
D. Object.freeze()
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 aboutrecordId.Which two options could a developer insert at the placeholder in line 02 to achieve this?Choose 2 answers
A. ‘Update’ , (recordId : ‘123abc’(
B. ‘Update’ , ‘123abc’
C. { type : ‘update’, recordId : ‘123abc’ }
D. ‘Update’ , { Details : { recordId : ‘123abc’ } }
A developer creates a simple webpage with an input field. When a user enters text in theinput field and clicks the button, the actual value of the field must be displayed in theconsole.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 withbutton.addEventListener(“onclick”, function() {
Refer to the following code:<html lang=”en”><body><div onclick = “console.log(‘Outer message’) ;”><button id =”myButton”>CLick me<button></div></body><script>function displayMessage(ev) {ev.stopPropagation();console.log(‘Inner message.’);}const elem =document.getElementById(‘myButton’);elem.addEventListener(‘click’ , displayMessage);</script></html>What will the console show when the button is clicked?
A. Outer message
B. Outer message Inner message
C. Inner message Outer message
D. Inner message
Refer to the code below:Async funct on functionUnderTest(isOK) {If (isOK) return ‘OK’ ;Throw new Error(‘not OK’);)Which assertion accuretely tests the above code?
A. Console.assert (await functionUnderTest(true), ‘ OK ’)
B. Console.assert (await functionUnderTest(true), ‘ not OK ’)
C. Console.assert (awaitfunctionUnderTest(true), ‘ not OK ’)
D. Console.assert (await functionUnderTest(true), ‘OK’)
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 isthe result of executing line 04?
A. 0
B. 6
C. -Infinity
D. RuntimeError
Refer to the code below:01 const server = require(‘server’);02 /* Insert code here */A developer imports a library that creates a web server.The imported library uses eventsandcallbacks to start the serversWhich 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) ;
A developer wants to iterate through an array of objects and count the objects and countthe objects whose property value, name, starts with the letter N.Const arrObj = [{“name” : “Zach”} , {“name” : “Kate”},{“name” : “Alise”},{“name” :“Bob”},{“name” :“Natham”},{“name” : “nathaniel”}Refer to the code snippet below:01 arrObj.reduce(( acc, curr) => {02 //missing line 0202 //missing line 0304 ).0);Which missing lines 02 and 03 return the correct count?
A. Const sum = curr.startsWith(‘N’) ? 1: 0;Return acc +sum
B. Const sum = curr.name.startsWith(‘N’) ? 1: 0;Return acc +sum
C. Const sum = curr.startsWIth(‘N’) ? 1: 0;Return curr+ sum
D. Constsum = curr.name.startsWIth(‘N’) ? 1: 0;Return curr+ sum
Giventhe 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 ]--
A developer is working on an ecommerce website where the delivery date is dynamicallycalculated based on the current day. The code line below is responsible for this calculation.Const deliveryDate = new Date ();Due to changes in the business requirements, the delivery date must now be today’sdate + 9 days.Which code meets thisnew 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;
Which function should a developer use to repeatedly execute code at a fixed interval ?
A. setIntervel
B. setTimeout
C. setPeriod
D. setInteria
developer is trying to convince management that their team will benefit from usingNode.js for a backend server that they are going to create. The server will be a web serverthathandles API requests from a website that the team has already built using HTML, CSS,andJavaScript.Which three benefits of Node.js can the developer use to persuade their manager?Choose 3 answers:
A. I nstalls with its own package manager toinstall 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. User non blocking functionality for performant request handling .
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) {
A developer wrote the following code: 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 thisbehavior?
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{ 04handleObjectValue(x); 05 } catch(error){ 06 handleError(error); 07 } 08 getNextValue();
D. 03 try { 04 handleObjectValue(x) 05 ……………………
Which three browser specific APIs are available for developers to persist data betweenpage loads ?Choose 3 answers
A. IIFEs
B. indexedDB
C. Global variables
D. Cookies
E. localStorage.
In the browser, the window object is often used to assign variables that require thebroadest scope in an application Node.js application does not have access to the windowobject by default.Which two methods are used to address this ?Choose 2 answers
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 variablesto module.exports and require them as needed.
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 personaliseContextneeds to be executed when the webpage is fully loaded (HTML content and all related files ), in order to do some custom initialization.Which statement should beused to call personalizeWebsiteContent 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);
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 agame : $(gamename) …`); 07 ) 08 function Console 16 Bit (name) { 09 GameConsole.call(this, name) ; 10 } 11 Console16bit.prototype = Object.create ( GameConsole.prototype) ;12 //insert code here 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 ’); What should a developer insert at line 15 to output the following message using the method ? > SNEGeneziz is loading a cartridgegame: 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) {
A team that works on a big project uses npm to deal with projects dependencies.A developer added a dependency does not get downloaded when they executenpminstall.Which two reasons could be possible explanations for this?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 added the dependency as a dev dependency, and NODE_ENV is set to production.
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
A class was written to represent items for purchase in an online store, and a second class Representing items that are on sale at a discounted price. THe constructor sets the nameto the first value passed in. The pseudocode is below: Class Item { constructor(name, price) { … // ConstructorImplementation } } 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 ‘This is a ’ + this.name; console.log(regItem.description());console.log(saleItem.description()); SaleItem.prototype.description = function () { return ‘This is a discounted ’ + 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. This is a Scarf This is a Shirt This is a Scarf This is a discounted Shirt
C. This is a Scarf This is a Shirt This is a discounted Scarf This is a discounted Shirt
D. Thisis aScarf Uncaught TypeError: saleItem.description is not a function This is a Shirt This is a did counted Shirt
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 runningline 05?
A. aPromise and bPromise run sequentially.
B. Neither aPromise or bPromise runs.
C. aPromise and bPromise run in parallel.
D. Only aPromise runs.
A developer has a formatName function that takes two arguments, firstName and lastNameand returns a string. They want to schedule thefunction 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');
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 2completed”));04 let car3 = new Promise(resolve => setTimeout (resolve, 3000, “Car 3Completed”));05 Promise.race([car1, car2, car3])06 .then(value => (07 let result = $(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.
Why would a developer specify a package.jason as a developed forge instead of adependency ?
A. It is required by the application in production.
B. It is only needed for local development and testing.
C. Other requiredpackages depend on it for development.
D. It should be bundled when the package is published.
A test has a dependency on database. query. During the test, the dependency is replacedwith an object called database with the method,Calculator query, that returns an array. The developer does notneed to verify how manytimes 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
A developer is creating a simple webpage with a button. When a userclicks this button for the first time, a message is displayed.The developer wrote the JavaScript code below, but something is missing. Themessage gets displayed every time a user clicks the button, instead of just the first time.01 functionlisten(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, useevent.stopPropagation ( ),
C. On line 04, use button.removeEventListener(‘ click” , listen);
D. On line 06, add an option called once to button.addEventListener().
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”
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 theresult of a previous promise.
C. .then() cannot be added after a catch.
D. .then() manipulates and returns the original promise.
Refer to the code below?LetsearchString = ‘ 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*/, ‘’);
developer wants to use a module nameduniversalContainersLib and them call functionsfrom it.How should a developer import every function from the module and then call the fuctionsfooand 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();
Which statement phrases successfully?
A. JSON.parse ( ‘ foo ’ );
B. JSON.parse ( “ foo ” );
C. JSON.parse( “ ‘ foo ’ ” );
D. JSON.parse(‘ “ foo ” ’);
Which two console logs outputs NaN?Choose 2 answers
A. console.log(10/ Number(‘5’));
B. console.log(parseInt(‘two’));
C. console.log(10/ ‘’five);
D. console.log(10/0);
Be part of the conversation — share your thoughts, reply to others, and contribute your experience.
Some asynchronous programming scenarios were quite detailed.
They test applying JavaScript concepts in real development situations.
Career question: does this certification help in frontend development careers?
Yes, it’s valuable for JavaScript and web development roles.
Some questions about prototypes and inheritance were new to me.
Those usually test object-oriented programming concepts in JavaScript.
Some long coding scenarios require careful reading.
Yes, especially asynchronous logic and debugging scenarios.
Technical question: how do closures work in JavaScript?
Most study material mentions closures retaining access to outer scope variables after execution.
Some case-based questions about closures and callbacks were detailed.
Those help understand functional programming and asynchronous execution.
Does the exam focus a lot on ES6 syntax and browser APIs?
Yes, promises, modules, and event handling are key topics.
Some scenario questions about API calls were interesting.
Those usually test asynchronous processing and fetch API concepts.
The study material I'm using focuses a lot on functions, arrays, and object manipulation.
Technical question: what is the purpose of async/await in JavaScript?
Most study material says async/await simplifies asynchronous code and improves readability.
Some practice questions about DOM manipulation and event handling were very helpful.
Agreed, especially understanding closures and scope concepts.
I started preparing for the Javascript-Developer-I exam using practice questions. JavaScript development concepts are quite detailed.
Yes, the study material explains ES6 features and asynchronous programming very clearly.
Kiran Abbas
Some browser API scenarios were detailed.
Robert Fischer
Yes, they test practical JavaScript development understanding.