Easily To Pass New Salesforce JS-Dev-101 Dumps with 149 Questions
Latest JS-Dev-101 Study Guides 2026 - With Test Engine PDF
NEW QUESTION # 65
Which three statements are true about promises ?
Choose 3 answers
- A. A fulfilled or rejected promise will not change states .
- B. A pending promise canbecome fulfilled, settled, or rejected.
- C. A settled promise can become resolved.
- D. The executor of a new Promise runs automatically.
- E. A Promise has a .then() method.
Answer: A,B,E
NEW QUESTION # 66
Refer to the string below.
Const str='Salesforce';
Which two statementsresults in the word 'Sales'?
Answer:
Explanation:
See the Answer below in explanation
NEW QUESTION # 67
A developer creates a new web server that uses Node.js. It imports a server library that uses events and callbacks for handling server functionality. The server library is imported with require and is made available to the code by a variable named server. The developer wants to log any issues that the server has while booting up.
Which code logs an error at boot time with an event?
- A. server.on('error', (error) => {
console.log('ERROR', error);
}); - B. server.error((error) => {
console.log('ERROR', error);
}); - C. try {
server.start();
} catch(error) {
console.log('ERROR', error);
} - D. server.catch((error) => {
console.log('ERROR', error);
});
Answer: A
Explanation:
Event-driven Node-style APIs expose events via .on(eventName, handler).
To listen for error events:
server.on('error', (error) => {
console.log('ERROR', error);
});
A and B assume methods .error or .catch that don't exist on typical event emitters.
C only catches synchronous errors from server.start(), not async event-based errors.
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NEW QUESTION # 68
Given the JavaScript below:
01 function filterDOM(searchString){
02 const parsedSearchString = searchString && searchString.toLowerCase();
03 document.querySelectorAll('.account').forEach(account => {
04 const accountName = account.innerHTML.toLowerCase();
05 account.style.display = accountName.includes(parsedSearchString) ? /* Insert code here */
06 });
07 }
Which code should replace the placeholder comment on line 05 to hide accounts that do not match the search string?
- A. 'visible' : 'hidden'
- B. 'none' : 'block'
- C. 'hidden' : 'visible'
- D. 'block' : 'none'
Answer: D
Explanation:
Comprehensive and Detailed Explanation From Exact Extract JavaScript knowledge:
Line 05 uses the conditional (ternary) operator:
condition ? valueIfTrue : valueIfFalse
In this specific code:
account.style.display = accountName.includes(parsedSearchString)
? /* valueIfTrue */
: /* valueIfFalse */;
accountName.includes(parsedSearchString) returns:
true if the accountName string contains the parsedSearchString,
false otherwise.
The requirement is:
Hide accounts that do not match the search string.
That means:
If the account name includes the search string → it should be visible.
If the account name does not include the search string → it should be hidden.
The relevant property is:
account.style.display
For the display property:
Common values for showing elements:
'block', 'inline', 'inline-block', etc.
Common value for hiding elements:
'none' (element is not rendered and takes up no space).
So we want:
When accountName.includes(parsedSearchString) is true → show the element, e.g. display = 'block'.
When false → hide the element, display = 'none'.
Therefore the assignment should be:
account.style.display = accountName.includes(parsedSearchString) ? 'block' : 'none'; This matches option A:
'block' : 'none'
Why other options are incorrect:
B . 'none' : 'block'
This would hide matching accounts and show non-matching accounts, which is the opposite of the requirement.
C . 'hidden' : 'visible'
These are not valid values for the display property; they belong to the visibility property (visibility: 'hidden' | 'visible'), not display.
D . 'visible' : 'hidden'
Same issue as C: not valid for display, and reversed logic compared to requirement.
Thus, to correctly show matching accounts and hide non-matching ones, the ternary must be:
'block' : 'none'
Reference of JavaScript knowledge documents or Study Guide (concept names only):
Conditional (ternary) operator condition ? exprIfTrue : exprIfFalse
String.prototype.includes for substring checks
DOM APIs: document.querySelectorAll and forEach on NodeLists
Element styling via element.style.display
CSS display property: block vs none
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NEW QUESTION # 69
Refer to the code below:
let car1 = new Promise((_ ,reject)=> setTimeout(reject,2000,"Car1 crashed in")); let car2 = new Promise(resolve => setTimeout(resolve,1500,"Car2 completed")); let car3 = new Promise(resolve => setTimeout(resolve,3000,"Car3 completed")); Promise.race([car1,car2,car3])
.then(value=>{
let result = `${value} the race.`;
}).catch(err=>{
console.log('Race is cancelled.',err);
});
What is the valueof result when promise.race execues?
Answer:
Explanation:
Car2 completed the race.
NEW QUESTION # 70
A developer at Universal Containers is creating their new landing pagebased on HTML, CSS, and JavaScript. The website includes multiple external resources that are loaded when the page is opened.
To ensure that visitors have a good experience, a script named personalizeWebsiteContent needs to be executed when the webpage isloaded and there is no need to wait for the resources to be available.
Which statement should be used to call personalizeWebsiteContent based on the above business requirement?
- A. windows,addEventListener('load', personalizeWebsiteContent);
- B. windows,addEventListener('DOMContent Loaded ', personalizeWebsiteContent);
- C. windows,addEventListener('onDOMCContentLoaded', personalizeWebsiteContent);
- D. windows,addEventListener('onload', personalizeWebsiteContent);
Answer: A
NEW QUESTION # 71
Refer to the code below:
What is the value of result when the code executes?
- A. 5-5
- B. 10-10
- C. 10-5
- D. 5-10
Answer: B
NEW QUESTION # 72
A developer wants to define a function log to be used a few times on a single-file JavaScript script.
01 // Line 1 replacement
02 console.log('"LOG:', logInput);
03 }
Which two options can correctly replaceline 01 and declare the function for use?
Choose 2 answers
- A. const log = (logInput) => {
- B. function leg(logInput) {
- C. const log(loginInput) {
- D. function log = (logInput) {
Answer: A,B
NEW QUESTION # 73
A developer writers the code below to calculate the factorial of a given number.
Function factorial(number) {
Return number + factorial(number -1);
}
factorial(3);
What is the resultof executing line 04?
- A. -Infinity
- B. RuntimeError
- C. 0
- D. 1
Answer: B
NEW QUESTION # 74
Given the JavaScript below:
01 function filterDOM(searchString){
02 const parsedSearchString = searchString && searchString.toLowerCase();
03 document.querySelectorAll('.account').forEach(account => {
04 const accountName = account.innerHTML.toLowerCase();
05 account.style.display = accountName.includes(parsedSearchString) ? /* Insert code here */;
06 });
07 }
Which code should replace the placeholder comment on line 05 to hide accounts that do not match the search string?
- A. 'visible' : 'hidden'
- B. 'none' : 'block'
- C. 'hidden' : 'visible'
- D. 'block' : 'none'
Answer: D
Explanation:
We have a ternary:
account.style.display = accountName.includes(parsedSearchString)
? /* if true */
: /* if false */;
Requirement:
If the account matches the search string → show it.
If it does not match → hide it.
For display:
Show: 'block' (or similar visible value).
Hide: 'none'.
So we want:
account.style.display = accountName.includes(parsedSearchString)
? 'block'
: 'none';
That corresponds to option A.
Why others are wrong:
B, C use values suitable for visibility, not display.
D ('none' : 'block') inverts the logic, hiding matches and showing non-matches.
________________________________________
NEW QUESTION # 75
A developer at Universal Containers creates a new landing page based on HTML, CSS, and JavaScript.
To ensure that visitors have a good experience, a script named personalizeWebsiteContent needs to be executed to do some custom initialization when the webpage is fully loaded with HTML content and all related files.
Which statement should be used to call personalizeWebsiteContent based on the above business requirement?
- A. window.addEventListener('load', personalizeWebsiteContent);
- B. document.addEventListener('DOMContentLoaded', personalizeWebsiteContent);
- C. window.addEventListener('onload', personalizeWebsiteContent);
- D. document.addEventListener('onDOMContentLoaded', personalizeWebsiteContent);
Answer: A
Explanation:
Comprehensive and Detailed Explanation From JavaScript Knowledge:
Two key browser events:
DOMContentLoaded (fired on document):
Fired when the HTML document has been completely loaded and parsed, without waiting for stylesheets, images, and subresources to finish loading.
load (fired on window):
Fired when the entire page is fully loaded, including all dependent resources such as stylesheets and images.
The requirement states:
"... when the webpage is fully loaded with HTML content and all related files." That matches the semantics of the load event on the window object.
So the correct code is:
window.addEventListener('load', personalizeWebsiteContent);
Why others are incorrect:
A: DOMContentLoaded fires earlier, when HTML is parsed, but before all related files (images, some styles, etc.) are guaranteed to be loaded.
B: 'onDOMContentLoaded' is not a valid event name; the event is 'DOMContentLoaded'.
D: When using addEventListener, the event type is 'load', not 'onload'. 'onload' is the name of the handler property (window.onload = ...), not the event string.
Relevant concepts: window.load event, DOMContentLoaded, addEventListener syntax, page load lifecycle.
________________________________________
NEW QUESTION # 76
At Universal Containers, every team has its own way of copyingJavaScript objects. The code snippet shows an Implementation from one team:
What is the output of the code execution?
- A. Hello Dan
- B. SyntaxError: Unexpected token in JSON
- C. Hello John Doe
- D. Hello Dan Doe
Answer: B
NEW QUESTION # 77
A developer has two ways to write a function:
Option A:
function Monster() {
This.growl = () => {
Console.log ("Grr!");
}
}
Option B:
function Monster() {};
Monster.prototype.growl =() => {
console.log("Grr!");
}
After deciding on an option, the developer creates 1000 monster objects.
How many growl methods are created with Option A Option B?
- A. 1 growl method is created for Option 1000 growl methods are created for Option B.
- B. 1000 growl method is created for Option A. 1 growl methods are created for Option
- C. 1000 growl methods are created regardless of which option is used.
- D. 1 growl method is created regardless of whichoption is used.
Answer: B
NEW QUESTION # 78
Cloud Kicks has a class to represent items for sale in an online store, as shown below:
Class Item{
constructor (name, price){
this.name = name;
this.price = price;
}
formattedPrice(){
return 's' + String(this.price);}}
A new business requirement comes in that requests a ClothingItem class that should have all of the properties and methods of the Item class but will also have properties that are specific to clothes.
Which line of code properly declares the clothingItem class such that it inherits from Item?
- A. Class ClothingItem {
- B. Class ClothingItem extends Item {
- C. Class ClothingItem super Item {
- D. Class ClothingItem implements Item{
Answer: B
NEW QUESTION # 79
Refer to the code below:
const searchText = 'Yay! Salesforce is amazing!';
let result1 = searchText.search(/sales/i);
let result2 = searchText.search(/sales/);
console.log(result1);
console.log(result2);
After running this code, which result is displayed on the console?
- A. 5
0 - B. true
false - C. 5
undefined - D. 5
-1
Answer: D
Explanation:
Comprehensive and Detailed Explanation From Exact Extract JavaScript Knowledge:
String: "Yay! Salesforce is amazing!"
Index positions:
'Y' at 0, 'a' at 1, 'y' at 2, '!' at 3, space at 4, 'S' at 5, 'a' at 6, 'l' at 7, 'e' at 8, 's' at 9, etc.
Substring "Sales" starts at index 5.
String.prototype.search with a regex returns the index of the first match or -1 if there is no match.
searchText.search(/sales/i);
/sales/i is case-insensitive because of the i flag.
It matches "Sales" beginning at index 5.
So result1 is 5.
searchText.search(/sales/);
/sales/ is case-sensitive.
It requires lowercase "sales".
The text has "Sales" with uppercase S, so this does not match.
search returns -1 when there is no match.
So result2 is -1.
Console output:
First log: 5
Second log: -1
Option D matches this.
Concepts: regex search, case sensitivity vs i flag, String.prototype.search return values.
________________________________________
NEW QUESTION # 80
Refer to the code below:
01 const myFunction = arr => {
02 return arr.reduce((result, current) => {
03 return result + current;
04 }, 10);
05 }
What is the output of this function when called with an empty array?
- A. Returns 0
- B. Returns NaN
- C. Returns 5 ← (Text here appears to be a typo; correct value is 10, see explanation.)
- D. Throws an error
Answer: C
Explanation:
Comprehensive and Detailed Explanation From JavaScript Knowledge:
We call:
myFunction([]);
Inside:
arr.reduce((result, current) => {
return result + current;
}, 10);
Key points about Array.prototype.reduce:
Signature: array.reduce(callback, initialValue)
If initialValue is provided and the array is empty, reduce:
Does not call the callback at all.
Simply returns initialValue.
Here:
arr is [] (empty).
initialValue is 10.
So:
No iterations of the callback happen (no elements to process).
The return value is the initial value: 10.
So the actual output is:
myFunction([]) === 10;
Among the options:
A: 0 - incorrect, because the initial value is 10, not 0.
B: Throws an error - reduce throws only if the array is empty and there is no initialValue. Here we have an initial value, so no error.
C: NaN - there is no arithmetic with undefined or invalid values; we just return 10.
D: Returns 5 - the numeric value given is wrong; the correct value is 10.
Given the logic, the correct conceptual result is 10. The option text "Returns 5" is almost certainly a typo for "Returns 10". Since the letter that is intended to represent the correct behavior is D, we keep:
Study Guide / Concept Reference (no links):
Array.prototype.reduce behavior with initialValue
Behavior of reduce on an empty array with and without initialValue
Return value when no iterations run
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NEW QUESTION # 81
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