Salesforce JS-Dev-101 JavaScript Certification Exam Dumps (V8.02) – Start with Salesforce Certified JavaScript Developer JS-Dev-101 Free Dumps (Part 1, Q1-Q34)

1. 01 function changeValue(obj) {

2 obj.value = obj.value / 2;

3 }

4 const objA = { value: 10 };

5 const objB = objA;

6

7 changeValue(objB);

8 const result = objA.value; What is the value of result?

2. 01 function Monster() { this.name = 'hello'; };

02 const m = Monster();

What happens due to the missing new keyword?

3. Refer to the code below:

let productSKU = '8675309';

A developer has a requirement to generate SKU numbers that are always 19 characters long, starting with 'sku', and padded with zeros.

Which statement assigns the value sku000000008675309?

4. Given the JavaScript below:

function onLoad() {

console.log("Page has loaded!");

}

Where can the developer see the log statement after loading the page in the browser?

5. Function to test:

01 const sum3 = (arr) => {

02 if (!arr.length) return 0;

03 if (arr.length === 1) return arr[0];

4 if (arr.length === 2) return arr[0] + arr[1];

5 return arr[0] + arr[1] + arr[2];

6 };

Which two assert statements are valid tests for this function?

6. A developer wants to advocate for a mature, well-supported web framework/library instead of a new one (Minimalist.js).

Which two should be recommended?

7. A test searches for:

<button class="blue">Checkout</button>

But the actual HTML is:

<button>Checkout</button>

The test fails because it expects a class that no longer exists.

What type of test outcome is this?

8. A developer creates a simple webpage with an input field.

When a user enters text and clicks the button, the actual value must be displayed in the console:

HTML:

<input type="text" value="Hello" name="input">

<button type="button">Display</button>

JavaScript:

01 const button = document.querySelector('button');

02 button.addEventListener('click', () => {

3 const input = document.querySelector('input');

4 console.log(input.getAttribute('value'));

5 });

When the user clicks the button, the output is always "Hello".

What needs to be done to make this code work as expected?

9. Refer to the code below:

01 let total = 10;

02 const interval = setInterval(() => {

03 total++;

4 clearInterval(interval);

5 total++;

6 }, 0);

7 total++;

8 console.log(total);

Considering that JavaScript is single-threaded, what is the output of line 08 after the code executes?

10. Code:

01 const sayHello = (name) => {

2 console.log('Hello ', name);

3 };

4

05 const world = () => {

6 return 'World';

7 };

8

9 sayHello(world);

This does not print "Hello World".

What change is needed?

11. A developer is asked to fix some bugs reported by users. To do that, the developer adds a breakpoint for debugging.

01 function Car(maxSpeed, color) {

2 this.maxSpeed = maxSpeed;

3 this.color = color;

4 }

5 let carSpeed = document.getElementById('carSpeed');

6 debugger;

7 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?

12. Refer to the code:

01 const event = new CustomEvent(

2 // Missing code

3 );

4 obj.dispatchEvent(event);

A developer needs to dispatch a custom event called update to send information about recordId.

Which two options can be inserted at line 02?

13. HTML:

<p> The current status of an Order: <span id="status"> In Progress </span> </p> Which JavaScript statement changes 'In Progress' to 'Completed'?

14. A developer wants to use a module called DatePrettyPrint. This module exports one default function called printDate().

How can the developer import and use printDate()?

15. A developer needs the function personalizeWebsiteContent to run when the webpage is fully loaded (HTML and all external resources).

Which implementation should be used?

16. A developer wants to create a simple image upload using the File API.

HTML:

<input type="file" onchange="previewFile()">

<img src="" height="200" alt="Image preview..." />

JavaScript:

01 function previewFile() {

02 const preview = document.querySelector('img');

3 const file = document.querySelector('input[type=file]').files[0];

4 // line 4 code

5 reader.addEventListener("load", () => {

6 preview.src = reader.result;

7 }, false);

8 // line 8 code

9 }

Which code in lines 04 and 08 allows the selected local image to be displayed?

17. A page loads 50+ <div class="ad-library-item"> elements, all ads. Developer wants to quickly and temporarily remove them. Options:

18. Given the JavaScript below:

01 function filterDOM(searchString){

2 const parsedSearchString = searchString && searchString.toLowerCase();

3 document.querySelectorAll('.account').forEach(account => {

4 const accountName = account.innerHTML.toLowerCase();

5 account.style.display = accountName.includes(parsedSearchString) ? /* Insert code here */

6 });

7 }

Which code should replace the placeholder comment on line 05 to hide accounts that do not match the search string?

19. catch(err => {

13 console.log("Race is cancelled.", err);

14 });

What is the value of result when Promise.race executes?

20. A Node.js server library uses events and callbacks. The developer wants to log any issues the server has at boot time.

Which code logs an error with an event?

21. catch(err => {

16 console.log("Race is cancelled.", err);

17 });

What is the value of result when Promise.race executes?

22. JavaScript:

01 function Tiger() {

2 this.type = 'Cat';

3 this.size = 'large';

4 }

5

6 let tony = new Tiger();

7 tony.roar = () => {

8 console.log('They're great!');

9 };

10

11 function Lion() {

12 this.type = 'Cat';

13 this.size = 'large';

14 }

15

16 let leo = new Lion();

17 // Insert code here

18 leo.roar();

Which two statements could be inserted at line 17 to enable line 18?

23. Which three actions can the code execute in the browser console?

24. Refer to the code below:

01 const objBook = {

2 title: 'JavaScript',

3 };

4 Object.preventExtensions(objBook);

5 const newObjBook = objBook;

6 newObjBook.author = 'Robert';

What are the values of objBook and newObjBook respectively?

25. Refer to the code below:

01 let o = {

02 get js() {

3 let city1 = String('St. Louis');

4 let city2 = String('New York');

5

6 return {

7 firstCity: city1.toLowerCase(),

8 secondCity: city2.toLowerCase(),

9 }

10 }

11 }

What value can a developer expect when referencing o.js.secondCity?

26. A developer creates a class that represents a news story based on the requirements that a Story should have a body, author, and view count.

The code is shown below:

01 class Story {

2 // Insert code here

3 this.body = body;

4 this.author = author;

5 this.viewCount = viewCount;

6 }

7 }

Which statement should be inserted in the placeholder on line 02 to allow for a variable to be set to a new instance of a Story with the three attributes correctly populated?

27. 1.A team at Universal Containers works on a big project and uses yarn to manage the project's dependencies.

A developer added a dependency to manipulate dates and pushed the updates to the remote repository. The rest of the team complains that the dependency does not get downloaded when they execute yarn.

What could be the reason for this?

28. A developer executes:

document.cookie;

document.cookie = 'key=John Smith';

What is the behavior?

29. Which statement accurately describes an aspect of promises?

30. Refer to the code below:

01 const addBy = ?

02 const addByEight = addBy(8);

03 const sum = addByEight(50);

Which two functions can replace line 01 and return 58 to sum?

31. Refer to the code below:

01 let country = {

02 get capital() {

3 let city = Number("London");

4

5 return {

6 cityString: city.toString(),

7 }

8 }

9 }

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

32. Which option is true about the strict mode in imported modules?

33. A developer needs to debug a Node.js web server because a runtime error keeps occurring at one of the endpoints.

The developer wants to test the endpoint on a local machine and make the request against a local server to look at the behavior. In the source code, the server.js file will start the server. The developer wants to debug the Node.js server only using the terminal.

Which command can the developer use to open the CLI debugger in their current terminal window?

(With corrected typing errors: node_inspect → node inspect, node_start_inspect → node start inspect.)

34. Given the following code:

let x = ('15' + 10) * 2;

What is the value of x?