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| Section | Weight | Objectives |
|---|---|---|
| Debugging and Error Handling | 7% | - Debugging tools and breakpoints - Console methods and logging - Error types and exception handling - Defensive programming practices |
| Asynchronous Programming | 13% | - Event loop and micro/macro tasks - Fetch API and HTTP requests - Promises and chaining - Async/await syntax - Callbacks and callback hell |
| Server-Side JavaScript | 8% | - Module system and require/import - Node.js fundamentals and runtime - Core Node.js modules - Command-line tools and scripts |
| Objects, Functions, and Classes | 25% | - Decorators and advanced function patterns - Class syntax, inheritance, and prototypes - Function definitions, parameters, and scope - Object creation, properties, and methods - Closures and execution context - Modules and imports/exports |
| Variables, Types, and Collections | 23% | - Array methods and data manipulation - JSON parsing and usage - Variable declaration and initialization - Working with strings, numbers, dates, and booleans - Type coercion and conversion rules - Truthy and falsy values |
| Testing | 7% | - Testing frameworks and assertions - Unit testing concepts - Code coverage and best practices - Test doubles and mocks |
| Browsers and Events | 17% | - Browser APIs and Web Storage - Event handling, propagation, and delegation - Document Object Model (DOM) manipulation - Window and document object properties - Script loading and execution order |
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NEW QUESTION # 63
Refer to the following code:
01 class Ship {
02 constructor(size) {
03 this.size = size;
04 }
05 }
06
07 class FishingBoat extends Ship {
08 constructor(size, capacity){
09 //Missing code
10 this.capacity = capacity;
11 }
12 displayCapacity() {
13 console.log( ' The boat has a capacity of ${this.capacity} people. ' );
14 }
15 }
16
17 let myBoat = new FishingBoat( ' medium ' , 10);
18 myBoat.displayCapacity();
Which statement should be added to line 09 for the code to display
The boat has a capacity of 10 people?
Answer: C
Explanation:
FishingBoat extends Ship, so it is a subclass. In ES6 classes:
* When you define a constructor in a subclass, you must call super(...) before accessing this.
* super(size) calls the parent class (Ship) constructor, which sets this.size = size.
So the correct constructor is:
class FishingBoat extends Ship {
constructor(size, capacity) {
super(size); // line 09
this.capacity = capacity;
}
displayCapacity() {
console.log(`The boat has a capacity of ${this.capacity} people.`);
}
}
Why others are incorrect:
* B. ship.size = size;
* ship is not defined; this would cause a ReferenceError.
* C. super.size = size;
* super is not an instance; you must call super(...) as a function to invoke the parent constructor.
* D. this.size = size;
* In a subclass constructor, you must call super() before using this, otherwise you get a ReferenceError. Also this bypasses the parent constructor logic.
Relevant concepts: ES6 class inheritance, extends, super() in subclass constructors, this initialization rules.
NEW QUESTION # 64
A developer wrote the following code:
01 let X = object.value;
02
03 try {
04handleObjectValue(X);
05 } catch (error) {
06 handleError(error);
07 }
Thedeveloper has a getNextValue function to execute after handleObjectValue(), but does not want to execute getNextValue() if an error occurs.
How can the developer change the code to ensure this behavior?
Answer: C
NEW QUESTION # 65
Refer to the code below:
01 const objBook = {
02 title: ' JavaScript ' ,
03 };
04 Object.preventExtensions(objBook);
05 const newObjBook = objBook;
06 newObjBook.author = ' Robert ' ;
What are the values of objBook and newObjBook respectively?
Answer: A
Explanation:
* Object.preventExtensions(obj) This built-in JavaScript method marks an object so that no new properties can be added to it. Existing properties can still be read and updated, but adding new ones is disallowed.
* const newObjBook = objBook; Both variables reference the same object in memory. JavaScript objects are assigned by reference, not copied.
* newObjBook.author = " Robert " ; Because the object has been marked as non-extensible, JavaScript will not allow new properties to be added. The behavior depends on mode:
* In non-strict mode: the assignment silently fails and does nothing.
* In strict mode: this would throw a TypeError.
Since nothing indicates strict mode, this is non-strict behavior, making the assignment fail silently.
Therefore, the object remains:
{ title: " JavaScript " }
Both objBook and newObjBook point to the same unchanged object.
This matches option A.
JavaScript knowledge references (text-only)
* Object.preventExtensions() prevents adding new properties.
* Assigning an object to another variable copies the reference, not the object.
* Adding a property to a non-extensible object silently fails in non-strict mode.
NEW QUESTION # 66
A developer creates a generic function to log custom messages in the console. To do this, the function below is implemented.
01 function logStatus(status){
02 console./*Answer goes here*/{'Item status is: %s', status};
03 }
Which three console logging methods allow the use of string substitution in line 02?
Answer: A,B,C
NEW QUESTION # 67
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: A
Explanation:
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 # 68
......
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