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| Section | Weight | Objectives |
|---|---|---|
| Server Side JavaScript | 8% | - Modules and file operations - Node.js applications - Salesforce API integration |
| Browser and Events | 17% | - DOM manipulation - Browser Developer Tools - Event handling, propagation, bubbling, and capturing |
| Debugging and Error Handling | 7% | - Logging strategies and debugging techniques - try-catch blocks |
| Testing | 7% | - Test-driven development principles - Automated testing strategies - Unit testing with Jest |
| Variables, Types, and Collections | 23% | - Array manipulation (map, filter, reduce, forEach, find) - JSON parsing and stringification - Type coercion and type conversion - String manipulation and Date objects - Variable declaration (var, let, const, scoping, hoisting) |
| Objects, Functions, and Classes | 25% | - JavaScript modules (export, import) - Higher-order functions and closures - Object creation, properties, and prototypal inheritance - ES6 Classes, constructors, methods, and inheritance - Function declarations, expressions, and arrow functions |
| Asynchronous Programming | 13% | - Event loop and asynchronous code execution - Callback patterns - Promises and async/await |
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NEW QUESTION # 112
Original code:
01 let requestPromise = client.getRequest;
03 requestPromise().then((response) => {
04 handleResponse(response);
05 });
The developer wants to gracefully handle errors from a Promise-based GET request.
Which code modification is correct?
Answer: D
Explanation:
________________________________________
Comprehensive and Detailed Explanation From Exact Extract JavaScript Knowledge Key JavaScript Promise rule:
try...catch does not catch asynchronous errors that occur in Promise chains.
Therefore, the correct way to handle errors in a Promise is:
promise.then(...).catch(...);
Analysis of options:
A and B:
Both wrap asynchronous code in try...catch, which does not catch Promise rejections.
try...catch only catches errors thrown synchronously inside the block.
C:
Correct. A .catch() on the Promise chain handles any error from the Promise returned by requestPromise().
D:
.finally() executes regardless of success or failure, but it does not receive the error object, so it cannot handle the error.
Thus the only valid solution is option C.
________________________________________
JavaScript Knowledge Reference (text-only)
Promise rejections must be handled with .catch().
try...catch only handles synchronous code.
.finally() does not receive a rejection reason.
NEW QUESTION # 113
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?
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 # 114
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 {
02 // Insert code here
03 this.body = body;
04 this.author = author;
05 this.viewCount = viewCount;
06 }
07 }
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?
Answer: D
Explanation:
Comprehensive and Detailed Explanation From Exact Extract JavaScript knowledge:
In ES6 class syntax, the special method used to initialize a new instance is called constructor.
A class definition syntax:
class ClassName {
constructor(param1, param2) {
this.prop1 = param1;
this.prop2 = param2;
}
}
The constructor method:
Is called automatically when you create a new instance with new ClassName(...).
Receives the arguments passed in the new expression.
Assigns values to this to set instance properties.
Applying this to Story
We want to be able to write:
const article = new Story('Some body', 'Author Name', 100);
and have:
article.body === 'Some body'
article.author === 'Author Name'
article.viewCount === 100
To achieve this, the class must have:
class Story {
constructor(body, author, viewCount) {
this.body = body;
this.author = author;
this.viewCount = viewCount;
}
}
So the correct line 02 is:
constructor(body, author, viewCount) {
Why the other options are incorrect
A . constructor() {
This defines a constructor with no parameters.
The lines inside the constructor use body, author, and viewCount, which would be undefined unless they exist in an outer scope (they normally do not).
This would lead to the instance properties being set to undefined in normal usage.
B . super(body, author, viewCount) {
super(...) is used inside a constructor of a subclass to call the parent class constructor.
You cannot use super(...) { as a method definition; this is invalid syntax in a class body.
Additionally, Story as given is not shown extending any class, so super is inappropriate here.
C . function Story(body, author, viewCount) {
Inside a class definition, you do not use the function keyword to define methods.
function Story(...) here would be invalid syntax in a class body.
Even if it were allowed, the special constructor method for a class is named constructor, not the class name.
Therefore, only:
constructor(body, author, viewCount) {
correctly declares the constructor for the Story class and ensures instances created with new Story(body, author, viewCount) have all three properties populated.
Reference / Study Guide concepts (no links):
ES6 class syntax
constructor method in classes
this and instance properties in classes
Difference between class constructors and regular functions
Invalid use of super and function inside class bodies
________________________________________
NEW QUESTION # 115
Given the code below:
01 const delay = async delay => {
02 return new Promise((resolve, reject) => {
03 console.log(1);
04 setTimeout(resolve, delay);
05 });
06 };
07
08 const callDelay = async () => {
09 console.log(2);
10 const yup = await delay(1000);
11 console.log(3);
12 };
13
14 console.log(4);
15 callDelay();
16 console.log(5);
What is logged to the console?
Answer: A
Explanation:
Comprehensive and Detailed Explanation From Exact Extract JavaScript Knowledge:
Execution order:
Top-level code runs synchronously:
Line 14: console.log(4); → logs 4.
Line 15: callDelay(); is called.
Inside callDelay:
Line 9: console.log(2); → logs 2.
Line 10: await delay(1000);:
Calls delay(1000).
Inside delay(1000):
Line 3: console.log(1); → logs 1.
Line 4: setTimeout(resolve, delay); schedules resolve in 1000 ms.
delay returns a pending Promise. await pauses callDelay here and returns control to the event loop.
Back to top-level:
Line 16: console.log(5); → logs 5.
So synchronous log sequence is: 4, 2, 1, 5.
After ~1000 ms:
The setTimeout in delay resolves the Promise.
The await in callDelay resumes.
Line 11: console.log(3); → logs 3.
Final log order: 4 2 1 5 3.
Both A and B show the same sequence; one must be chosen, so A is correct.
Concepts: async/await flow, Promise resolution timing, event loop, and ordering of synchronous vs timer callbacks.
________________________________________
NEW QUESTION # 116
Code:
01 let array = [1, 2, 3, 4, 4, 5, 4, 4];
02 for (let i = 0; i < array.length; i++) {
03 if (array[i] === 4) {
04 array.splice(i, 1);
05 i--;
06 }
07 }
What is the value of array after execution?
Answer: D
Explanation:
________________________________________
Comprehensive and Detailed Explanation From Exact Extract JavaScript Knowledge Initial array:
[1, 2, 3, 4, 4, 5, 4, 4]
The loop removes every value equal to 4:
array.splice(i, 1) removes the element at index i and shifts all later elements left.
i-- ensures the next index is checked correctly after the shift, preventing skipping elements.
Step-by-step removal:
Remove the first 4 → array becomes [1,2,3,4,5,4,4]
Remove next 4 → [1,2,3,5,4,4]
Remove next 4 → [1,2,3,5,4]
Remove last 4 → [1,2,3,5]
Final result:
[1,2,3,5]
Option B is correct.
________________________________________
JavaScript Knowledge Reference (text-only)
splice(index, deleteCount) removes elements and shifts remaining items.
Adjusting the loop index when deleting prevents skipping items.
Arrays update length dynamically after splice().
NEW QUESTION # 117
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