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

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

The correct answers are A, C, and E .

Node.js allows JavaScript to run outside the browser. That makes it useful for backend development, command-line tools, APIs, real-time applications, and server-side services.

A is correct because Node.js executes JavaScript on the server side.

A team that already knows:

HTML

CSS

JavaScript

can use JavaScript for backend development as well. This reduces the need to switch to a completely different backend language.

Example:

const http = require( ' http ' );

const server = http.createServer((req, res) = > {

res.end( ' Hello from Node.js ' );

});

server.listen(3000);

This is server-side JavaScript.

C is correct because Node.js uses a non-blocking, event-driven model.

For API servers, this is valuable because Node.js can handle many I/O operations without blocking the entire process while waiting for tasks like:

database queries

file reads

network requests

API responses

Instead of waiting synchronously, Node.js can register callbacks, promises, or async functions and continue handling other work.

E is correct because Node.js commonly installs with npm, the Node Package Manager.

npm is used to install and manage third-party libraries, such as:

Express

Socket.IO

dotenv

Jest

Axios

This makes it easier to build backend applications using reusable packages.

Now review the incorrect answers:

B is incorrect because JavaScript is not primarily a static-analysis language by default. Node.js executes JavaScript at runtime. Static checking can be added with tools such as TypeScript, ESLint, or other analyzers, but that is not an inherent Node.js benefit.

D is incorrect because Node.js does not release one major version only every few years. Its release cycle is more frequent than that, so this is not an accurate benefit statement.

Therefore, the verified answers are A, C, and E .

The correct answer is C .

The browser provides the History API through:

window.history

To add a new entry to the browser’s session history without refreshing the page, JavaScript uses:

window.history.pushState(state, title, url);

So the valid statement is:

window.history.pushState(newStateObject, ' ' , null);

This updates the browser history stack without forcing a full page reload. It is commonly used in single-page applications when changing views or routes dynamically.

The method accepts three arguments:

window.history.pushState(stateObject, title, url);

stateObject stores custom data associated with the history entry.

title is usually passed as an empty string because many browsers ignore it.

url optionally changes the displayed URL. Passing null means no new URL is provided.

Option A is incorrect because:

window.customHistory

is not the standard browser History API object.

Option B is incorrect because:

createState()

is not a valid History API method.

Option D is incorrect because:

updateState()

is not a valid History API method.

The correct browser API method is:

window.history.pushState()

Therefore, the verified answer is C .

This code uses:

A for...of loop to iterate over values in array.

break to exit the loop entirely when output > 10.

continue to skip even numbers.

It sums only certain numbers into output.

Let’s walk through the loop step by step.

Initial values:

array = [1,2,3,4,5,6,7,8,9,10,11]

output = 0

Loop: for (let num of array) { ... }

First iteration: num = 1

Line 05: if (output > 10) → 0 > 10 is false → no break.

Line 08: if (num % 2 == 0) → 1 % 2 == 1, not 0, so false → no continue.

Line 11: output += num → output = 0 + 1 = 1.

Second iteration: num = 2

output > 10 → 1 > 10 is false → no break.

num % 2 == 0 → 2 % 2 == 0, so true → continue.

Because of continue, line 11 is skipped.

output remains 1.

Third iteration: num = 3

output > 10 → 1 > 10 is false.

num % 2 == 0 → 3 % 2 == 1, false → no continue.

output += num → output = 1 + 3 = 4.

Fourth iteration: num = 4

output > 10 → 4 > 10 is false.

num % 2 == 0 → 4 % 2 == 0, true → continue.

Skip sum; output remains 4.

Fifth iteration: num = 5

output > 10 → 4 > 10 is false.

num % 2 == 0 → 5 % 2 == 1, false.

output += num → output = 4 + 5 = 9.

Sixth iteration: num = 6

output > 10 → 9 > 10 is false.

num % 2 == 0 → 6 % 2 == 0, true → continue.

output remains 9.

Seventh iteration: num = 7

output > 10 → 9 > 10 is false.

num % 2 == 0 → 7 % 2 == 1, false.

output += num → output = 9 + 7 = 16.

Eighth iteration would be num = 8, but:

At the top of the loop body, line 05 is checked again:

if (output > 10) → 16 > 10 is true, so break; is executed.

When break runs:

The loop terminates immediately.

No further iterations (for num = 8, 9, 10, 11) are executed.

Therefore, output stays at 16.

Final value of output after the loop ends is 16.

This matches option A.

Why other options do not match:

B. 25: Would require adding more odd numbers (e.g., 9, 11) after 7, but the loop stops early due to output > 10.

C. 11: Would be smaller; the actual sum of 1 + 3 + 5 + 7 until break is 16.

D. 36: Would require summing many more values (e.g., most or all odd numbers up to 11), but again, the break condition stops the loop once output exceeds 10.

So:

Answer: A

JavaScript knowledge / Study Guide references (concept names only, no links):

for...of loop over arrays

break statement in loops (terminating a loop early)

continue statement in loops (skipping to the next iteration)

Modulo operator % to test even and odd numbers

Step-by-step execution and control flow in loops