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| Section | Weight | Objectives |
|---|---|---|
| Topic 1: Debugging and Error Handling | 7% | - Console methods for debugging - Custom error types - Breakpoints and code inspection - Error handling techniques (try/catch/finally) |
| Topic 2: Objects, Functions, and Classes | 25% | - Object creation and manipulation - Variable scope and closures - Prototypal inheritance - Modules and decorators - Function declarations and expressions - ES6 classes and inheritance - Execution flow and context - Higher-order functions - Arrow functions |
| Topic 3: Server Side JavaScript | 8% | - Core Node.js modules - CLI commands - Node.js fundamentals - Server-side JavaScript implementations - Package management (npm) |
| Topic 4: Browser and Events | 17% | - Event propagation (bubbling and capturing) - DOM manipulation - Browser-specific APIs - Browser Developer Tools usage - Interacting with forms and user input - Event handling and listeners |
| Topic 5: Testing | 7% | - Writing and modifying unit tests - Unit testing concepts - Test coverage and reliability - Test effectiveness evaluation |
| Topic 6: Asynchronous Programming | 13% | - Event loop and execution flow - Async/Await syntax - Asynchronous patterns for business requirements - Callbacks - Promises (creation, chaining, error handling) |
| Topic 7: Variables, Types, and Collections | 23% | - Strings, numbers, and dates - Arrays and collections - Primitive and complex data types - Type coercion and conversion - JSON parsing and manipulation - Variable declarations and initialization - Truthy and falsy evaluations |
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NEW QUESTION # 139
Refer to following code block:
Let array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,];
Let output =0;
For (let num of array){
if (output >0){
Break;
}
if(num % 2 == 0){
Continue;
}
Output +=num;
What is the value of output after the code executes?
Answer: B
NEW QUESTION # 140
function myFunction() {
a = a + b;
var b = 1;
}
myFunction();
console.log(a);
console.log(b);
Which statement is correct?
Answer: A
Explanation:
The correct answer is A , not D.
Inside myFunction(), the declaration:
var b = 1;
is hoisted to the top of the function scope, but only the declaration is hoisted, not the assignment. So internally, JavaScript treats the function approximately like this:
function myFunction() {
var b;
a = a + b;
b = 1;
}
Now examine this line:
a = a + b;
Before JavaScript can assign a value to a, it must first evaluate the right-hand side:
a + b
At this point:
b
exists locally because var b was hoisted, so its value is:
undefined
However:
a
has not been declared anywhere. Reading an undeclared variable causes a:
ReferenceError
So this line throws an error before assignment happens:
a = a + b;
Because the error occurs on that line, the next line inside the function is never executed:
var b = 1;
Also, because the error is not handled with try...catch, the program stops before reaching:
console.log(a);
console.log(b);
Therefore, the accurate statement is:
Line 02 throws a reference error, therefore line 03 is never executed.
So the verified answer is A .
NEW QUESTION # 141
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 # 142
What are two unique features of fat-arrow functions compared to normal function definitions?
Answer: B,D
Explanation:
Arrow functions have two defining characteristics:
* Implicit return when written as a single expression:
* const fn = () = > 5; // returns 5 automatically
This is unique to arrow functions # A is correct.
* Lexical this binding : Arrow functions do not create their own this. Instead, they use the this value from the surrounding scope # B is correct.
Incorrect options:
* C is false: There is no special argument called parentThis.
* D is the opposite of arrow function behavior: Normal functions create their own this; arrow functions do not.
JavaScript Knowledge References (text-only)
* Arrow functions have lexical this binding.
* Arrow functions support implicit return for single expressions.
NEW QUESTION # 143
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 value of result when promise.race execues?
Answer: A
NEW QUESTION # 144
......
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