Salesforce Certified JavaScript Developer (JS-Dev-101): JavaScript-Developer-I Exam
"Salesforce Certified JavaScript Developer (JS-Dev-101)", also known as JavaScript-Developer-I exam, is a Salesforce Certification. With the complete collection of questions and answers, PrepPDF has assembled to take you through 149 Q&As to your JavaScript-Developer-I Exam preparation. In the JavaScript-Developer-I exam resources, you will cover every field and category in Salesforce Developer Certification helping to ready you for your successful Salesforce Certification.
PrepPDF offers free demo for JavaScript-Developer-I exam (Salesforce Certified JavaScript Developer (JS-Dev-101)). You can check out the interface, question quality and usability of our practice exams before you decide to buy it.
- Exam Code: JavaScript-Developer-I
- Exam Name: Salesforce Certified JavaScript Developer (JS-Dev-101)
- Certification Provider: Salesforce
- Corresponding Certification: Salesforce Developer
- Updated: Sep 23, 2026
- No. of Questions: 149 Questions & Answers with Testing Engine
- Download Limit: Unlimited
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JavaScript-Developer-I Practice Q&A's
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Salesforce JavaScript-Developer-I Exam Overview:
| Certification Vendor: | Salesforce |
|---|---|
| Exam Name: | Salesforce Certified JavaScript Developer I Exam |
| Exam Number: | JS-Dev-101 / JavaScript-Developer-I |
| Certificate Validity Period: | No expiration; requires regular maintenance via Trailhead modules |
| Related Certifications: | Salesforce Certified Lightning Web Components Specialist Salesforce Certified Platform Developer I |
| Available Languages: | Japanese, English |
| Exam Format: | Multiple-select, Multiple-choice |
| Passing Score: | 65% |
| Real Exam Qty: | 60 scored + up to 5 unscored |
| Exam Price: | USD 200 (+ applicable taxes) |
| Exam Duration: | 105 minutes |
| Recommended Training: | Salesforce JavaScript Developer I Certification Prep |
| Exam Registration: | Salesforce Certification Registration |
| Sample Questions: | DOWNLOAD DEMO |
| Exam Way: | Online proctored or onsite at authorized testing centers |
| Pre Condition: | No formal prerequisites; 1–2 years of JavaScript development experience recommended |
| Official Syllabus URL: | https://trailhead.salesforce.com/credentials/javascript-developer-i |
Salesforce JavaScript-Developer-I Exam Syllabus Topics:
| Section | Weight | Objectives |
|---|---|---|
| Debugging and Error Handling | 7% | - Defensive programming practices - Error types and exception handling - Console methods and logging - Debugging tools and breakpoints |
| Asynchronous Programming | 13% | - Callbacks and callback hell - Fetch API and HTTP requests - Event loop and micro/macro tasks - Async/await syntax - Promises and chaining |
| Variables, Types, and Collections | 23% | - Array methods and data manipulation - Variable declaration and initialization - Truthy and falsy values - Type coercion and conversion rules - Working with strings, numbers, dates, and booleans - JSON parsing and usage |
| Browsers and Events | 17% | - Document Object Model (DOM) manipulation - Script loading and execution order - Window and document object properties - Browser APIs and Web Storage - Event handling, propagation, and delegation |
| Server-Side JavaScript | 8% | - Module system and require/import - Core Node.js modules - Command-line tools and scripts - Node.js fundamentals and runtime |
| Testing | 7% | - Test doubles and mocks - Unit testing concepts - Code coverage and best practices - Testing frameworks and assertions |
| Objects, Functions, and Classes | 25% | - Closures and execution context - Function definitions, parameters, and scope - Decorators and advanced function patterns - Modules and imports/exports - Object creation, properties, and methods - Class syntax, inheritance, and prototypes |
JavaScript-Developer-I Exam FAQ: The Details That Matter
The Salesforce Certified JavaScript Developer (JS-Dev-101) exam requires 65% to pass, and registration costs USD 200 (+ applicable taxes). A failed attempt means paying the same fee again — a readiness check with the PrepPDF engines before booking is the cheaper option.
Salesforce recommends these training resources for the Salesforce Certified JavaScript Developer (JS-Dev-101) exam:
Follow the training with steady self-testing — the 149 practice questions from PrepPDF help you apply theory and fill any gaps the training leaves.
The JavaScript-Developer-I exam is a Salesforce certification exam validating the Salesforce Certified JavaScript Developer (JS-Dev-101) syllabus shown above. It belongs to these credential paths: Salesforce Certified Platform Developer I, Salesforce Certified Lightning Web Components Specialist. Candidates in 2026 prepare for it with PrepPDF's 149 practice questions, available as a printable PDF, a Windows Desktop Test Engine, and an Online Test Engine — three versions of the same materials.
PrepPDF issues a full refund if you take the Salesforce Certified JavaScript Developer (JS-Dev-101) exam within 60 days of purchase and do not pass. The policy does not apply if the exam is taken within 3 days of purchase, if the exam was never actually taken, or to free materials or expired orders, and the candidate name must match the payer name. Submit a scan of your enrollment slip and the official Score Report PDF within 2 days of the exam; claims are processed within 7 days. Alternatively, exchange for two free exam products of equal value and keep your original update service. Orders arrive by email within 1 minute — contact support if nothing arrives within 2 hours.
Online proctored or onsite at authorized testing centers Register for the Salesforce Certified JavaScript Developer (JS-Dev-101) exam through these official channels:
After booking, PrepPDF delivers your practice questions within 1 minute — preparation starts the same day.
The Salesforce Certified JavaScript Developer (JS-Dev-101) exam contains 60 scored + up to 5 unscored to complete within 105 minutes. Timed simulation in the PrepPDF Desktop Test Engine teaches that rhythm before exam day does.
The official Salesforce Certified JavaScript Developer (JS-Dev-101) outline defines 7 domains. The leading three are Objects, Functions, and Classes (25%), Variables, Types, and Collections (23%), and Browsers and Events (17%). The full list is in the topics section above, and PrepPDF's 149 practice questions cover each one.
Three versions of the same study materials: a printable, expert-prepared PDF with free demo download and instant access; a Desktop Test Engine for Windows that simulates the real exam with two practice modes and works offline; and an Online Test Engine for any browser on Windows, Mac, Android, and iOS with test history and performance review. All 149 practice questions are identical across versions. Every purchase includes 365 days of free updates — whenever a new version is compiled, it is sent to you automatically — plus a 50% renewal discount afterward and unlimited computer installations.
No formal prerequisites; 1–2 years of JavaScript development experience recommended Since requirements change over time, confirm the latest on the official Salesforce exam page before scheduling.
Salesforce Certified JavaScript Developer (JS-Dev-101) Sample Questions:
Refer to the code:
01 console.log( ' Start ' );
02 Promise.resolve( ' Success ' ).then(function(value) {
03 console.log( ' Success ' );
04 });
05 console.log( ' End ' );
What is the output after the code executes successfully?
- A. Start
Success
End - B. Success
Start
End - C. Start
End
Success - D. End
Start
Success
Correct Answer: C 🗳️
Explanation: Only visible for PrepPDF members. You can sign-up / login (it's free).
After user acceptance testing, the developer is asked to change the webpage background based on the user's location. It works on the developer's computer but not on the tester's machine.
Which two actions will help determine accurate results?
- A. The developer should rework the code.
- B. The tester should disable their browser cache.
- C. The developer should inspect their browser refresh settings.
- D. The tester should clear their browser cache.
Correct Answer: B,D 🗳️
Explanation: Only visible for PrepPDF members. You can sign-up / login (it's free).
Refer to the code below:
let inArray = [ [1, 2], [3, 4, 5] ];
Which two statements result in the array [1, 2, 3, 4, 5]?
(With corrected typing errors: usArray # inArray, .. # ....)
- A. [].concat.apply({}, inArray);
- B. [].concat.apply(inArray, [] );
- C. [].concat::...inArray();
- D. [].concat(...inArray);
Correct Answer: A,D 🗳️
Explanation: Only visible for PrepPDF members. You can sign-up / login (it's free).
Refer to the code below:
01 function myFunction(reassign) {
02 let x = 1;
03 var y = 1;
04
05 if (reassign) {
06 let x = 2;
07 var y = 2;
08 console.log(x);
09 console.log(y);
10 }
11
12 console.log(x);
13 console.log(y);
14 }
What is displayed when myFunction(true) is called?
- A. 2 2 1 1
- B. 2 2 2 2
- C. 2 2 undefined undefined
- D. 2 2 1 2
Correct Answer: D 🗳️
Explanation: Only visible for PrepPDF members. You can sign-up / login (it's free).
Refer to the code below:
let strNumber = ' 12345 ' ;
Which code snippet shows a correct way to convert this string to an integer?
- A. let numberValue = Integer(strNumber);
- B. let numberValue = textValue.toInteger();
- C. let numberValue = Number(strNumber);
- D. let numberValue = (number) textValue;
Correct Answer: C 🗳️
Explanation: Only visible for PrepPDF members. You can sign-up / login (it's free).
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