Updated for Summer '26
New to this track? Our Salesforce Certified Platform Developer exam prep is the recommended first step. See our certification path to understand where this certification fits. The Salesforce Certified JavaScript Developer exam weights LWC and Aura most heavily (30%) — see the full breakdown, study tips, and practice questions below. See our full study guide for deep section coverage. Ready to book? Read our exam tips and study plan.
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Updated for Summer '26
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Who is the JavaScript Developer I exam for?
- Front-end developers entering Salesforce: You have strong JavaScript fundamentals and want to build Lightning Web Components on the Salesforce Platform.
- Salesforce developers broadening skills: You already work with Apex and want to validate your modern JavaScript and LWC expertise for full-stack Salesforce development.
- Web developers transitioning to enterprise: You have experience with React, Angular, or Vue and want to apply your component-based skills within the Salesforce ecosystem.
Exam Fees & Registration
Exam Fee
$200
One-time registration fee
Retake Fee
$100
If you need to retake the exam
Comparing certs? View all Salesforce exam fees in one place →
Certification Validity
Your Salesforce Certified JavaScript Developer certification is valid for 3 years from the date you pass the exam. You'll need to maintain your certification through continuing education or retake the exam.
How to Register
Register for the Salesforce Certified JavaScript Developer (CRT-600) exam through the official Salesforce certification portal.
Register for ExamExam data verification: questions, duration, passing score, fees, and section coverage were checked against official source references on .
Official sources: Exam guide·Salesforce exam pricing·Independent prep resource; no braindumps or leaked exam questions.
Salesforce Certified JavaScript Developer – Complete Summer '26 Guide
This exam tests core JavaScript (ES6+), async programming, and Lightning Web Components on the Salesforce Platform. Expect code-reading questions on closures, promises, the event loop, and LWC lifecycle hooks — strong JS fundamentals matter more than Salesforce-specific knowledge.
Recommended Prerequisites
We recommend completing this certification first to prepare you better.
Salesforce Certified JavaScript Developer Exam Weightage by Section
Exam Topics
Exam Tips
- 1LWC and Aura are 30%—know component lifecycle, decorators, and events.
- 2JavaScript fundamentals: ES6+, async, DOM, and debugging.
- 3Understand when to use LWC vs Aura and migration considerations.
- 4Testing: Jest for LWC, and debugging in browser and VS Code.
Prerequisites
- •JavaScript experience
- •Platform Developer I recommended
Focus Areas
- •JavaScript Fundamentals
- •LWC and Aura
- •Debugging and Testing
- •Performance
Study Strategy
Build at least two LWCs (one with Apex).
Practice debugging and unit testing.
Memorize key decorators and lifecycle hooks.
Exam Format and First-Attempt Readiness
The Salesforce Certified JavaScript Developer exam has 60 questions in 105 min, passing score 65%. Most Salesforce exams test scenario-based decisions — focus on when to use each feature, not just terms.
- Study LWC and Aura and JavaScript Fundamentals first — together they carry 55% of the exam.
- Do timed question sets. Build pacing and confidence.
- Review why wrong answers are wrong. It improves scenario reasoning.
- Book the exam once your mock scores are steady above 65%.
Is the JavaScript Developer I Exam Hard?
Is the JavaScript Developer I Exam Hard?
The JavaScript Developer I exam is moderately difficult. It is a JavaScript-first exam that happens to run on Salesforce — strong ES6+ fundamentals matter more than platform-specific knowledge, which catches many Salesforce-only developers off guard.
- 60 multiple-choice questions in 105 minutes.
- ~68% passing score — you can miss roughly 19 questions, but code-reading questions take time so pacing matters.
- Heavy on ES6+ and async patterns — closures, promises, async/await, the event loop, and prototype chain questions dominate the first half of the exam.
- LWC lifecycle knowledge required — expect scenario questions on connectedCallback vs renderedCallback, @wire vs imperative Apex calls, and Shadow DOM event propagation.
Pass Rate Guidance
Score 75%+ on 3 timed practice exams before booking — focus extra time on closures, promise chaining, and LWC lifecycle hooks.
JavaScript Developer I Exam Format Explained
JavaScript Developer I Exam Format Explained
The exam is proctored online or in-person. Here is the format:
Total Questions
60 scored questions
Time Limit
105 min
Passing Score
65%
Question Type
Multiple-choice & multiple-select
How Many Questions Are Scenario-Based?
About 40-50% of questions are scenario-based. Common patterns include reading a code snippet and predicting console output, choosing the correct LWC decorator for a data-fetching requirement, and identifying the right async pattern for a given use case.
Best Way to Pass on Your First Attempt
- Drill ES6+ code output questions: Practice reading arrow functions, destructuring, spread/rest, and template literals — the exam shows code and asks what it returns or logs.
- Master the event loop: Understand the difference between microtasks (promises) and macrotasks (setTimeout) and be able to predict execution order in code snippets.
- Know LWC decorators cold: @api for public properties, @wire for reactive data binding, and when to use imperative Apex calls instead of @wire.
- Understand Shadow DOM boundaries: Know how events propagate across shadow boundaries (composed:true), how CSS encapsulation works, and what LockerService/Lightning Web Security restricts.
JavaScript Developer I: Key Concepts for the Exam
JavaScript ES6+ Fundamentals
The exam tests modern JavaScript syntax. let and const for block-scoped variables (never var). Arrow functions and lexical this binding. Destructuring for arrays and objects. Template literals (backtick strings). Spread/rest operators. Promises for async operations. async/await for readable async code. The exam presents code snippets and asks about scoping, closures, prototype chain, or async behaviour — understanding ES6+ is the foundation for LWC development.
Web Component Standards (W3C)
Lightning Web Components are built on Web Component standards: Custom Elements (define new HTML elements), Shadow DOM (encapsulated styles and markup), HTML Templates (declarative rendering). Understanding these standards is tested because LWC implements them directly. Shadow DOM encapsulation means CSS from outside cannot affect component internals by default. The exam tests how the Shadow DOM affects event propagation (events do not cross shadow boundaries unless composed:true is set).
Lightning Web Components: Lifecycle and Reactivity
LWC lifecycle hooks: connectedCallback (component added to DOM), disconnectedCallback (removed from DOM), renderedCallback (after every render). @track (now redundant — all properties are reactive by default), @api (public property, set by parent), @wire (reactive data binding to Apex or platform adapters). The exam tests which lifecycle hook to use for a given scenario — connectedCallback for initial data fetch, renderedCallback for post-render DOM manipulation (with caution).
Apex Integration: @wire and Imperative Calls
@wire automatically calls Apex and re-calls when parameters change — use for read-only data that should refresh reactively. Imperative calls (calling Apex directly like a JS function) are used when you need explicit control — on button click, or when combining results. @wire uses the getRecord and getFieldValue adapters from lightning/uiRecordApi for record access. The @AuraEnabled(cacheable=true) annotation is required on Apex methods called via @wire. The exam tests which approach to use for a given data-fetching scenario.
Security in LWC and LockerService
Locker Service is Salesforce's security architecture for Lightning components — it isolates components from each other and restricts access to the DOM. LWC uses Lightning Web Security (LWS) — similar isolation but more permissive for standard APIs. The exam tests what Locker/LWS prevents (direct DOM manipulation of other components, eval(), dangerous APIs). Permission checks should be done server-side in Apex, not in the component (UI checks can be bypassed). CRUD and FLS enforcement belongs in the @AuraEnabled Apex method, not the component.
LWC source is written once, but two different JS engines run it at two different times: Node.js compiles/bundles and runs Jest tests at build time; the browser executes the compiled component, handles the Shadow DOM, and fires lifecycle hooks at runtime.
How to Pass the Salesforce JavaScript Developer I Exam
The JavaScript Developer I exam tests core JavaScript and modern web concepts applied in the Salesforce context. Treat it as a JavaScript fundamentals exam first — LWC knowledge is important, but strong ES6+ and async programming foundations are what carry candidates through.
Master ES6+ Syntax
Arrow functions, destructuring, spread/rest operators, template literals, modules (import/export), and classes are heavily tested. Know how each differs from ES5 equivalents and common pitfalls.
Promises & Async/Await
Understand the Promise lifecycle (pending, fulfilled, rejected), chaining with .then()/.catch()/.finally(), and how async/await is syntactic sugar over promises. Know how errors propagate and how Promise.all() works.
Closures, Scope & 'this'
These classic JavaScript topics appear frequently. Understand lexical scope, how closures capture variables from outer functions, and the four rules that determine what 'this' refers to (default, implicit, explicit, new binding).
LWC Lifecycle & Reactivity
Know the LWC component lifecycle hooks: constructor, connectedCallback, renderedCallback, disconnectedCallback. Understand reactive properties, how @track (legacy) and @api work, and how the wire service fetches data reactively.
The Event Loop & Web APIs
Understand call stack, event loop, microtask queue (promises), and macrotask queue (setTimeout). Know the fetch API, async patterns for HTTP calls, and how LWC's shadow DOM restricts direct DOM manipulation.
Is the Salesforce Certified JavaScript Developer (CRT-600) Exam Hard?
DifficultyModerate; plan about 4-8 weeks of focused prep.
Book When ReadyScore 80%+ on three timed mocks before scheduling.
Use Practice, Not DumpsOriginal practice questions build skill without risking your credential.
Exam format: 60 questions, 105 min, 65% passing score.
Get the Full CRT-600 Question Bank
Most candidates book the exam after scoring 75%+ on full mocks.
If you’re planning to test this quarter, aim to complete full mocks at least 10–14 days before your exam date.
Want to ensure you pass on your first try? Contact us for more information on our full 60-question mock exams and a personalized study plan. You can also reach out to km.krishnamohan25@gmail.com.
Request Mock Exams & Study PlanSalesforce Certified JavaScript Developer (CRT-600) Exam FAQs
- What is covered on the Salesforce Certified JavaScript Developer (CRT-600) exam?
- The Salesforce Certified JavaScript Developer (CRT-600) exam—formerly Salesforce Certified JavaScript Developer I— covers section-wise weightage as shown above. Use the exam topics and practice questions on this page to align your study with the official outline.
- Do I need Platform Developer I before JavaScript Developer I?
- While not required, Platform Developer I is highly recommended. JavaScript Developer I focuses specifically on JavaScript, LWC, and Aura, so having PD1 knowledge helps, but you can take it independently if you have strong JavaScript skills.
Next Certifications After Developer
After this certification, common next steps in the developer track: