Promise.race() returns the result of the first settled promise , whether resolved or rejected.

The promises:

car1 → rejects in 2000 ms

car2 → resolves in 1500 ms

car3 → resolves in 3000 ms

The earliest settled promise is car2 (1500 ms), which resolves with the value:

" Car 2 completed "

Therefore, Promise.race enters the .then() branch with:

value = " Car 2 completed "

Inside the .then():

let result = ' $(value) the race. ' ;

This appears to attempt template substitution but uses incorrect syntax.

JavaScript template literals require backticks and ${expression}, for example:

`${value} the race.`

Because the code is incorrect, result is literally the string:

$(value) the race.

However, the question asks:

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

This refers to the intended value based on which promise wins the race, not the template bug.

The winning value is:

Car 2 completed

So the correct conceptual answer is:

Car 2 completed the race.

JavaScript Knowledge References (text-only)

Promise.race() returns the first settled (resolved or rejected) promise.

The earliest resolve here is car2 (1500 ms).

Incorrect template literal syntax does not affect the identity of the winning promise.

setInterval(fn, delay, arg1, arg2, ...) calls fn every delay ms, passing extra arguments.

To call isDeg every 60 seconds with " cat " :

setInterval(isDeg, 60000, ' cat ' );

Why others are wrong:

A/D: isDeg( ' cat ' ) is called immediately, and its return value is scheduled, not the function.

C: setTimeout runs once after 60 seconds, not repeatedly.

If the dependency was added as a dev dependency (yarn add --dev), it goes into devDependencies.

When NODE_ENV=production, Yarn (and npm) typically skip devDependencies on install.

Thus the package doesn’t get installed for other team members in a production environment.

YARN_ENV is not a standard variable, --save is npm syntax (and Yarn saves by default), and --add is not how Yarn works (the command itself is yarn add).

The correct answer is C .

The original option contains a typing error. It should use the existing variable name:

let numberValue = Number(strNumber);

The value of strNumber is a string:

' 12345 '

Using Number() converts the numeric string into a JavaScript number:

12345

So after execution:

typeof numberValue;

returns:

" number "

Professional review of each option:

Option

Result

Explanation

A

Incorrect

JavaScript does not have a standard global Integer() conversion function.

B

Incorrect

Strings do not have a standard .toInteger() method.

C

Correct

Number(strNumber) correctly converts ' 12345 ' into 12345.

D

Incorrect

This is not valid JavaScript casting syntax.

A commonly used alternative would also be:

let numberValue = parseInt(strNumber, 10);

But from the provided answer choices, the verified answer is C .

We need to track the value of counter and the timing of each call to logCounter.

Initial state:

Line 01: counter = 0;

Line 02–04: logCounter logs the current value of counter.

Execution order and timing:

Line 05: logCounter();

Called immediately at time t = 0 ms.

counter is 0.

First log: 0.

Line 06: setTimeout(logCounter, 2100);

Schedules logCounter to run once after 2100 ms.

No log yet at this line.

Line 07–10: setInterval(() = > { counter++; logCounter(); }, 1000);

Schedules a repeating callback every 1000 ms (1 second).

First interval callback runs at t ≈ 1000 ms.

Now follow the timeline:

t = 0 ms:

logCounter(); from line 05

Logs: 0

t = 1000 ms (first interval execution):

counter++; → counter goes from 0 to 1.

logCounter(); logs 1.

t = 2000 ms (second interval execution):

counter++; → counter goes from 1 to 2.

logCounter(); logs 2.

t = 2100 ms (timeout from line 06):

logCounter(); runs again.

counter is still 2 (next setInterval will be at t = 3000 ms).

Logs 2.

So the first four logs are:

0

1

2

2

Concatenated as in the options: 0122.

Therefore, the correct choice is:

Answer: A

Study Guide / Concept References (no links):

setTimeout and setInterval timing behavior

Order of execution in the event loop

Closures capturing variables (here, logCounter using counter)

Understanding asynchronous scheduling in JavaScript

Initial values:

first = ' Who '

second = ' What '

Execution:

Inner try/catch/finally:

Line 05: throw new Error( ' Sad trombone ' );

Control goes to the inner catch.

Inner catch (lines 06–08):

catch (err) {

first = ' Why ' ;

throw err;

}

first is set to ' Why ' .

The error is rethrown.

Inner finally (lines 09–11):

finally {

second = ' When ' ;

}

finally runs whether or not there was an error.

second becomes ' When ' .

After inner finally, the rethrown error continues to propagate to the outer catch.

Outer catch (lines 12–14):

} catch (err) {

second = ' Where ' ;

}

Because the inner try rethrew, the outer catch runs.

It sets second = ' Where ' .

Final values:

first was changed to ' Why ' in the inner catch and never changed again.

second became ' When ' in the inner finally, and then ' Where ' in the outer catch.

So:

first is ' Why '

second is ' Where '

Option B is correct.

Concepts: nested try/catch/finally, rethrowing errors, order of execution for catch vs finally, variable mutation through error propagation.

A recursive function is a function that calls itself and has a base case to terminate the recursion.

Evaluate each option:

Option A:

const sumToTen = numVar = > {

if (numVar < 0)

return;

return sumToTen(numVar + 1);

};

This function calls itself: sumToTen(numVar + 1) — so it is recursive.

However, the base condition is if (numVar < 0) return;.

If you call sumToTen(0):

numVar < 0 is false, so it calls sumToTen(1), then sumToTen(2), and so on, incrementing forever.

There is no condition to stop the recursion when numVar increases; it will eventually cause a stack overflow.

This code does not represent a properly working recursive function with a valid termination for increasing values and is not a good example of correct recursion.

Option B:

function factorial(numVar) {

if (numVar < 0) return;

if (numVar === 0) return 1;

return numVar - 1;

}

This function does not call itself anywhere.

It has conditional returns, but there is no recursive call such as factorial(numVar - 1).

Therefore, it is not recursive at all.

Option C:

const factorial = numVar = > {

if (numVar < 0) return;

if (numVar === 0) return 1;

return numVar * factorial(numVar - 1);

};

This is a classic recursive factorial implementation.

It calls itself with a smaller argument: factorial(numVar - 1).

Base cases:

If numVar < 0, it simply returns (could be treated as invalid input).

If numVar === 0, it returns 1, which is the mathematical definition of 0! (zero factorial).

For positive integers, it correctly multiplies numVar by factorial(numVar - 1) until it reaches the base case.

This is a correct and working recursive function.

Option D (corrected):

let countingDown = function(startNumber) {

if (startNumber > 0) {

console.log(startNumber);

return countingDown(startNumber - 1);

} else {

return startNumber;

}

};

This function also calls itself: countingDown(startNumber - 1).

Base case:

When startNumber is not greater than 0 (i.e., 0 or negative), it returns startNumber and stops recursing.

For example, countingDown(3) would:

Log 3, call countingDown(2)

Log 2, call countingDown(1)

Log 1, call countingDown(0)

At 0, it hits the else branch and returns 0, ending the recursion.

This is a valid working recursive function structure (once syntax is corrected).

Therefore, the snippets that show working recursive functions are:

Answer: C, D

Study Guide / Concept References (no links):

Definition of recursion: a function calling itself

Base case vs recursive step

Recursive factorial implementation

Recursive countdown example

Importance of a terminating condition to avoid infinite recursion

Comprehensive and Detailed Explanation:

The loop removes every 4:

Start: [1, 2, 3, 4, 4, 5, 4, 4]

i=0 → 1 (no change)

i=1 → 2 (no change)

i=2 → 3 (no change)

i=3 → 4 → splice removes index 3 → [1,2,3,4,5,4,4], then i-- → 2

Next loop, i=3 → 4 again → splice → [1,2,3,5,4,4], i-- → 2

i=3 → 5 (no change)

i=4 → 4 → splice → [1,2,3,5,4] , i-- → 3

i=4 → 4 → splice → [1,2,3,5], i-- → 3

Next i=4, array.length is 4 → loop ends.

All 4s removed, final array: [1, 2, 3, 5].

Comprehensive and Detailed Explanation:

Evaluate step by step:

' 15 ' + 10

+ with a string operand performs string concatenation.

10 is coerced to ' 10 ' .

Result: ' 1510 ' .

' 1510 ' * 2

* always performs numeric multiplication.

' 1510 ' is converted to the number 1510.

1510 * 2 = 3020.

So x is 3020.

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.

==================================================