Full-Stack Development Developer 3

Question 1

Which of the following best describes the difference between `==` and `===` in JavaScript?

Accepted Answer

`===` checks value and type; `==` performs type coercion before comparing

Answer

`===` (strict equality) compares both value and type with no coercion, while `==` converts types before comparing.

Question 2

What is the primary advantage of using a message queue (e.g., RabbitMQ, Redis Streams) in a full-stack application?

Accepted Answer

It decouples producers and consumers, allowing async processing

Answer

Message queues allow different parts of the system to communicate asynchronously, improving resilience and scalability.

Question 3

In CSS, what is the box model and which property controls the sizing behavior?

Accepted Answer

The set of boxes (content, padding, border, margin) that wrap every element; controlled by `box-sizing`

Answer

The CSS box model describes the rectangular boxes generated for elements, and `box-sizing: border-box` makes width/height include padding and border.

Question 4

What does the `async/await` syntax in JavaScript do under the hood?

Accepted Answer

Wraps Promises so they can be written in a synchronous-looking style

Answer

`async/await` is syntactic sugar over Promises; `await` pauses execution of the async function until the Promise resolves.

Question 5

When should you use `useMemo` in a React component?

Accepted Answer

To cache the result of an expensive computation between renders

Answer

`useMemo` caches the result of a function and recomputes it only when its dependencies change, avoiding expensive recalculations on every render.

Full-Stack Development Practice Test