Salesforce Certified JavaScript Developer I Dumps & Exam Questions

Ace the Salesforce Certified JavaScript Developer I exam with our updated 2025 dumps, sample questions, and practical test sets. These materials are aligned with the latest exam blueprint and cover essential JavaScript concepts like ES6+, asynchronous programming, browser APIs, event handling, as well as Salesforce-specific topics like Lightning Web Components (LWC). Whether you're a frontend dev or aiming to become a certified JavaScript developer in the Salesforce ecosystem, our Salesforce Certified JavaScript Developer I dumps help sharpen your skills, improve accuracy, and ensure you're well-prepared to clear the exam on the first try.

Salesforce Certified JavaScript Developer I Dumps & Sample Questions List :

1. What is the output? `console.log(typeof NaN);`

1. `"undefined"`

2. `"number"`

3. `"NaN"`

4. `"string"`

2. Which of the following is a fundamental characteristic of a function declared with the `async` keyword?

1. It always returns a Promise.

2. It can only be called by another `async` function.

3. It blocks the main JavaScript thread until it completes.

4. It can use the `await` keyword, but only if it's inside a `try...catch` block.

3. To debug a Node.js application named `server.js` using the built-in command-line debugger, which command should a developer run?

1. `node server.js`

2. `node inspect server.js`

3. `node --inspect-brk server.js`

4. `node server.js --debug`

4. What does `console.log(Boolean(''))` output?

1. `true`

2. `TypeError`

3. `false`

4. `undefined`

5. A developer adds a testing library to `devDependencies` in `package.json`. When another developer on the team runs `yarn install`, the library is not installed. What is the most likely reason?

1. The yarn cache is corrupt and needs to be cleared with `yarn cache clean`.

2. The `yarn.lock` file was not committed to the repository.

3. The `NODE_ENV` environment variable is set to `production` on the other developer's machine.

4. The developer missed the `--save` flag.

6. Which tool bundles JavaScript modules?

1. ESLint

2. Jest

3. Babel

4. Webpack

7. What is the primary role of the `await` keyword in an `async` function?

1. It can only be used with the `fetch()` API.

2. It blocks the entire JavaScript program until a task is complete.

3. It pauses the execution of the `async` function until a Promise is settled.

4. It converts a regular value into a Promise.

8. Given the function: `const sayHello = () => console.log('Hi!');`. Which code snippet will execute this function exactly once, after a delay of 2 seconds?

1. `setTimeout(sayHello(), 2000);`

2. `setTimeout(sayHello, 2000);`

3. `setInterval(sayHello, 2000);`

4. `delay(sayHello, 2000);`

9. A quality assurance test for a "Buy Now" button passes. Later, a developer removes a CSS class that the test uses to identify the button, causing the test to fail, even though the button is still visible and functional for a user. What type of test result does this failure represent?

1. False Positive

2. True Positive

3. True Negative

4. False Negative

10. What is the output of `['a', 'b'].map(item => item.toUpperCase())`?

1. `[65, 66]`

2. `['A','b']`

3. `['A', 'B']`

4. `['a', 'b']`

11. What does `setTimeout(() => {}, 0)` accomplish?

1. Execution after render cycle

2. Higher priority than promises

3. Immediate execution

4. Guaranteed execution before I/O

12. Which Node.js method reads environment variables?

1. `process.getEnv()`

2. `fs.readEnvSync()`

3. `env.get()`

4. `process.env.VAR_NAME`

13. A developer wants to catch a potential error from an asynchronous operation inside a `setTimeout`. Which `try...catch` implementation is correct for this purpose?

1. `setTimeout(function() { try { countSheep(); } catch (e) { handleError(e); } }, 1000);`

2. `setTimeout(countSheep).catch(e => handleError(e))`

3. `new Promise(() => countSheep()).catch(e => handleError(e))`

4. `try { setTimeout(function() { countSheep(); }, 1000); } catch (e) { handleError(e); }`

14. Which React hook replaces `componentDidMount` for data fetching?

1. `useState`

2. `useEffect`

3. `useCallback`

4. `useMemo`

15. An `async` function `runParallel()` is defined, which returns a promise. Which statement shows the standard 'Promise chaining' syntax to execute the function and handle its successful result?

1. `runParallel().then(function(data){ ... });`

2. `runParallel().done(function(data){ ... });`

3. `runParallel().then(data);`

4. `async runParallel().then(data);`

16. What executes first: `Promise.resolve()` or `setTimeout(fn, 0)`?

1. Random order

2. Synchronous code

3. `setTimeout`

4. `Promise.resolve()`

17. What is logged? `let a = [1,2]; let b = [1,2]; console.log(a == b);`

1. `true`

2. `[1,2] == [1,2]`

3. `false`

4. `TypeError`

18. Which CSS-in-JS library uses tagged template literals?

1. JSS

2. Emotion

3. Tailwind CSS

4. styled-components

19. Given the code: `const pi = 3.1415926;` What is the data type of the variable `pi`?

1. Float

2. Integer

3. Number

4. Double

20. Which method safely accesses `document` in Next.js?

1. `useDocument()`

2. `global.document`

3. `next/document` component

4. `typeof window !== 'undefined'`

21. When debugging JavaScript in a browser's developer tools and paused at a breakpoint, which two of the following are fundamental panels for inspecting the program's state? (Choose 2)

1. Performance Panel

2. Call Stack Panel

3. Sources Panel

4. Scope Panel

22. A developer wants an event listener on a button to fire only the very first time it is clicked. Which two of the following approaches will achieve this? (Choose 2)

1. Inside the handler, explicitly remove the listener using `button.removeEventListener('click', myHandler);`.

2. `button.addEventListener('click', myHandler, { once: true });`

3. Inside the handler, call `event.stopPropagation();`.

4. Inside the handler, check a global flag like `if (hasFired) return;` and then set `hasFired = true;`.

23. What is the primary purpose of the `useState` hook in React?

1. To access context values

2. To manage side effects like data fetching

3. To optimize performance with memoization

4. To store and update component state

24. What is the output of `console.log(typeof null);` in JavaScript?

1. `"null"`

2. `primitive"`"

3. `undefined"`"

4. `object"`"

25. A developer writes `console.log('Page loaded!');` inside a function that runs on page load. Where will this message appear?

1. On the webpage itself, visible to the user.

2. On the browser's JavaScript console

3. In a new `alert()` pop-up window

4. On the terminal console running the web server

26. Given a nested array `let inArray = [[1, 2], [3, 4], [5]];`, which two statements will produce a new, flattened array `[1, 2, 3, 4, 5]`? (Choose 2)

1. `[].concat.apply([], inArray);`

2. `[].concat(...inArray);`

3. `inArray.flat();`

4. `inArray.concat();`

27. Which option is true about JavaScript modules (files imported via `import`) regarding strict mode?

1. Strict mode is disabled by default, but can be enabled with a `'use strict';` directive.

2. Strict mode only applies if the module is imported using a dynamic `import()`.

3. Strict mode is enabled by default, but can be disabled with a `'use no-strict';` directive.

4. JavaScript modules are always in strict mode, with no way to opt out.

28. A developer is creating an image previewer. The user selects a file using an `<input type='file'>`. Which code correctly reads the selected file and prepares it to be used as the `src` for an `<img>` tag?

1. `const reader = new File(); if (file) { reader.readAsDataURL(file); }`

2. `const reader = new FileReader(); if (file) { reader.readAsText(file); }`

3. `const reader = new FileReader(); if (file) { URL.createObjectURL(file); }`

4. `const reader = new FileReader(); if (file) { reader.readAsDataURL(file); }`

FAQs

1. What is the Salesforce Certified JavaScript Developer I certification?

This certification validates your skills in building applications using JavaScript and the Salesforce Lightning Platform. It focuses on JavaScript fundamentals and how they integrate with Salesforce features.

2. How do I get Salesforce Certified JavaScript Developer I certification?

You must pass the Salesforce JavaScript Developer I (CRT-600) exam. It measures your understanding of JavaScript concepts, testing frameworks, and application development on Salesforce.

3. What are the prerequisites for Salesforce Certified JavaScript Developer I?

There are no official prerequisites, but it’s recommended to have basic JavaScript knowledge and experience with Salesforce platform development.

4. How much does the Salesforce JavaScript Developer I exam cost?

The exam costs $200 USD, and retakes are priced at $100 USD, excluding local taxes.

5. What topics are included in the Salesforce JavaScript Developer I exam?

The exam covers topics like Variables, Data Types, Objects, Functions, DOM Manipulation, Event Handling, Asynchronous Programming, and Testing in JavaScript.

6. Is Salesforce JavaScript Developer I certification difficult?

It’s considered moderately challenging, requiring a solid understanding of core JavaScript concepts and how they apply within Salesforce.

7. How long does it take to prepare for Salesforce JavaScript Developer I?

Most candidates take 6–8 weeks of preparation with consistent coding practice, mock exams, and hands-on Salesforce experience.

8. What is the passing score for Salesforce Certified JavaScript Developer I?

You need a 65% score or higher to pass the certification exam.

9. Is Salesforce JavaScript Developer I certification worth it?

Yes. It’s valuable for developers aiming to validate their JavaScript skills and improve job prospects in Salesforce development.

10. What are the best resources to prepare for Salesforce Certified JavaScript Developer I exam?

Use Salesforce Trailhead modules, the official exam guide, and CertiMaan’s exam dumps, mock tests, and practice questions to boost your preparation.