Salesforce Updated JavaScript-Developer-I Exam Questions and Answers by santino

The correct answers are A, B, and D .

The two variables are:

let str1 = ' Java ' ;

let str2 = ' Script ' ;

The goal is to combine them into:

JavaScript

Option A is correct because template literals can insert variables directly into a string:

`${str1}${str2}`

This becomes:

`${ ' Java ' }${ ' Script ' }`

Result:

JavaScript

Option B is correct because strings have a concat() method:

str1.concat(str2);

This joins str2 onto the end of str1.

Result:

JavaScript

Option D is correct because the + operator performs string concatenation when both operands are strings:

str1 + str2;

This becomes:

' Java ' + ' Script '

Result:

JavaScript

The incorrect options:

Option C is not valid JavaScript for joining strings. const is used for declaring constants, not concatenating values.

Option E is incorrect because join() is an array method, not a string method. This would only work with an array, for example:

[ ' Java ' , ' Script ' ].join( ' ' );

But str1 is a string, so:

str1.join(str2)

is invalid.

Therefore, the verified answers are A, B, and D .

JSON.stringify(john) converts the john object into a JSON string.

When you JSON.parse that string back, you get a plain object :

Only data that can be represented in JSON is preserved (numbers, strings, booleans, arrays, plain objects).

Functions are not preserved and are dropped.

So dan is a plain object with properties firstName and lastName, but no name method .

Therefore, dan.name is undefined, and dan.name() throws:

TypeError: dan.name is not a function

The literal string interpolation inside console.log( ' Hello ${...} ' ) is also wrong (single quotes), but the code never reaches that line.

The code:

let timerId = setInterval(timedFunction, 1000);

setInterval schedules timedFunction to run every 1000 ms.

It returns an interval ID (here stored in timerId), which is used to cancel the interval later.

To cancel:

Use clearInterval(timerId);

This is the standard browser (and Node.js) API:

let id = setInterval(fn, delay);

clearInterval(id); stops future executions of that interval.

Check other options:

B. removeInterval(timerId);

There is no removeInterval function in the standard JavaScript timer API.

C. removeInterval(timedFunction);

Again, no such function; and timers are cancelled by ID, not by the callback function reference.

D. clearInterval(timedFunction);

clearInterval expects the ID returned by setInterval, not the callback function.

Passing the function does not cancel the timer.

Therefore, the correct statement is:

Answer: A

Study Guide / Concept References (no links):

Timer APIs: setInterval and clearInterval

Relationship between timer ID and cancellation

Difference between interval ID and callback function

Basic async timing patterns in JavaScript

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