Salesforce-JavaScript-Developer Exam Questions With Explanations

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Salesforce Salesforce-JavaScript-Developer Exam Sample Questions 2025

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22214 already prepared
Salesforce Spring 25 Release1-Jan-2026
221 Questions
4.9/5.0

Refer to the code below

Which value can a developer expect when referencing country,capital,cityString?

A. 'London'

B. undefined

C. An error

D. 'NaN'

D.   'NaN'

Universal Containers recently launched its new landing page to host a crowd-funding campaign. The page uses an external library to display some third-party ads. Once the page is fully loaded, it creates more than 50 new HTML items placed randomly inside the DOM, All the elements includes the same ad-library-item class, They are hidden by default, and they are randomly displayed while the user navigates through the page.

A. Use the DOM inspector to prevent the load event to be fired.

B. Use the browser to execute a script that removes all the element containing the class ad-library-item.

C. Use the DOM inspector to remove all the elements containing the class ad-library-item.

D. Use the browser console to execute a script that prevents the load event to be fired.

B.   Use the browser to execute a script that removes all the element containing the class ad-library-item.

Explanation:

Since the ads are generated dynamically after load and may reappear randomly, manually deleting them via the DOM inspector (option C) is impractical and one-off. Preventing the load event (options A and D) could break page functionality. Instead, injecting a small JavaScript snippet in the browser console to select all elements with .ad-library-item and remove them ensures you can rerun it at any time to clean up all current and newly inserted ads. For example:
document.querySelectorAll('.ad-library-item').forEach(el => el.remove());

Refer to the code snippet below: Let array = [1, 2, 3, 4, 4, 5, 4, 4]; For (let i =0; i < array.length; i++){ if (array[i] === 4) { array.splice(i, 1); } } What is the value of the array after the code executes?

A. [1, 2, 3, 4, 5, 4, 4]

B. [1, 2, 3, 4, 4, 5, 4]

C. [1, 2, 3, 4, 5, 4]

D. [1, 2, 3, 5]

C.   [1, 2, 3, 4, 5, 4]

A developer is asked to fix some bugs reported by users. To do that, the developer adds a breakpoint for debugging. Function Car (maxSpeed, color){
This.maxspeed =masSpeed;
This.color = color;
Let carSpeed = document.getElementById(‘ CarSpeed’);
Debugger;
Let fourWheels =new Car (carSpeed.value, ‘red’);
When the code execution stops at the breakpoint on line 06, which two types of information are available in the browser console ?
(Choose 2 answers)

A. The values of the carSpeed and fourWheels variables

B. A variable displaying the number of instances created for the Car Object.

C. The style, event listeners and other attributes applied to the carSpeed DOM element

D. The information stored in the window.localStorage property

A.   The values of the carSpeed and fourWheels variables
C.   The style, event listeners and other attributes applied to the carSpeed DOM element

Explanation:

At the moment the code pauses at debugger, the browser console gives you access to everything that’s been declared and initialized before that line. That means:
carSpeed has already been assigned using document.getElementById('CarSpeed'), so you can inspect its value — which is a DOM element.
You can also explore that DOM element’s properties, including its styles, attributes, and any event listeners attached to it.

However:
fourWheels hasn’t been created yet — it’s declared after the debugger line — so it won’t be available until you step forward in execution.
JavaScript doesn’t automatically track how many instances of an object have been created unless you explicitly code for it.
window.localStorage is always accessible, but it’s not directly tied to this code or breakpoint unless you’re interacting with it.

So the two correct answers are:
A. The values of the carSpeed and fourWheels variables — partially true, but only carSpeed is available at the breakpoint.
C. The style, event listeners and other attributes applied to the carSpeed DOM element — absolutely true and inspectable.

What are two unique features of functions defined with a fat arrow as compared to normal function definition?
Choose 2 answers

A. The function generated its own this making it useful for separating the function’s scope from its enclosing scope.

B. The function receives an argument that is always in scope, called parentThis, which is the enclosing lexical scope. C. If the function has a single expression in the function body,
the expression will be evaluated and implicit returned.

C. The function uses the this from the enclosing scope.

A.   The function generated its own this making it useful for separating the function’s scope from its enclosing scope.
C.   The function uses the this from the enclosing scope.

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Frequently Asked Questions

Focus on modular, reusable components. Make sure you understand component lifecycle hooks, event handling, and communication between parent and child components. Practice creating custom components that interact with Apex controllers and handle asynchronous data.
Use Promises or async/await patterns in JavaScript to manage server calls. Always handle error scenarios using try/catch blocks or .catch() on Promises. In exams, expect to explain how your code prevents UI blocking and ensures data consistency.
Leverage browser DevTools to inspect console logs, network calls, and event propagation. For LWC, use the Lightning Component Debug Mode. Check Apex responses for errors and ensure proper JSON parsing before using data in the UI.
Minimize unnecessary DOM manipulations, use track and @api/@wire decorators properly, and avoid repeatedly querying the server. Lazy-load data where possible and batch Apex calls to reduce server round trips. Efficient components are a common exam scenario.
For hands-on exercises, sample problems, and exam-focused tips, check salesforceking.com. It provides practical examples specifically designed to simulate real Salesforce JavaScript Developer exam scenarios.