JavaScript Developer I Exam Preparation Material | Salesforce Certified JavaScript Developer I

Prepare for the JavaScript Developer I with reliable study materials, practice questions, and key exam insights.

Prepare for the JavaScript Developer I Salesforce Certified JavaScript Developer I exam with CertQueen's independently developed study resources. Review important concepts, practice scenario-based questions, and use clear explanations to identify areas that require further study.

Question#1

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) {

Question#2

Cloud Kicks has a class to represent items for sale in an online store, as shown below:
Class Item{
constructor (name, price){
this.name = name;
this.price = price;
}
formattedPrice(){
return ‘s’ + String(this.price);}}
A new business requirement comes in that requests a ClothingItem class 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 clothingItem class such that it inherits from Item?

A. Class ClothingItem implements Item{
B. Class ClothingItem {
C. Class ClothingItem super Item {
D. Class ClothingItem extends Item {

Question#3

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();
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.getTime()
C. console.trace()
D. console.timeStamp()

Question#4

Consider type coercion, what does the following expression evaluate to?
True + 3 + ‘100’ + null

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

Question#5

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 ’).innerHTM
E. lenght*e

Exam Code: JavaScript Developer I
Q & A: 230 Q&As         Updated:  Sep 27,2026

 

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Review Key Concepts

Review the technologies, products, processes, and practical skills covered by the current JavaScript Developer I exam objectives.

Practice Scenario-Based Questions

Work through independently developed questions designed to strengthen your understanding of technical scenarios and decision-making.

Identify Knowledge Gaps

Use your results and the provided explanations to find weaker areas and focus your study more effectively.

How to Use This JavaScript Developer I Preparation Material

Review the Exam Scope

Start by reviewing the topics covered by the JavaScript Developer I exam. Compare them with the official exam objectives to understand the required technologies, operational tasks, and practical skills, then identify the areas that deserve the most attention.

Practice Independently

Complete a focused set of practice questions for each topic. On your first attempt, avoid referring to notes, answers, or other study resources so that you can evaluate your current understanding more accurately.

Study the Explanations

Review the answers and explanations after completing each practice session. Understand why the correct option is appropriate for the given scenario and why the other options may be incorrect or less suitable.

Close Knowledge Gaps

Keep track of incorrect answers, unfamiliar concepts, and weaker knowledge areas. Review these topics using official documentation and practical experience, then answer the related questions again to reinforce your understanding and monitor your progress.

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