JavaScript-Developer-I Exam Dumps : Salesforce Certified JavaScript Developer (JS-Dev-101)

The question is about:

Web frameworks that run on Node.js

Used to build servers and APIs

With established communities.

From the given options:

Angular:

A front-end framework running in the browser, not a Node.js server framework.

Gatsby:

A React-based static site generator; uses Node tooling but is not primarily a Node server framework.

Next / Next.js:

Server-side rendering / full-stack frameworks built on Node.js and React.

Used to create both server-rendered pages and APIs.

They have active communities and are “seasoned” compared to a hypothetical Minimalist.js.

Although typical Node back-end frameworks would include Express.js, Koa, or NestJS, given the options provided, the best fits for server-side frameworks with Node.js and an ecosystem are:

Next (interpreted as Next.js)

Next.js

Thus, the correct pair from the list is B and D.

Concepts: Node.js web frameworks, server-side rendering, community-backed frameworks vs minimal/new frameworks.

This question focuses on the typeof operator and how JavaScript represents the type of the value null.

Declaration on line 1:

let x = null;

Here:

x is explicitly assigned the value null.

In JavaScript, null is a special primitive value that represents “no value” or “empty value”.

Line 2:

console.log(typeof x);

The typeof operator returns a string indicating the type of the operand. For example:

typeof 1 returns " number "

typeof " hello " returns " string "

typeof true returns " boolean "

typeof undefined returns " undefined "

typeof {} returns " object "

typeof [] returns " object " (arrays are objects)

typeof function() {} returns " function "

For null, due to an early design decision in JavaScript, the result is:

typeof null === " object "

This is a known historical quirk of the language:

Although null is a primitive and conceptually means “no object”, typeof null returns the string " object " .

Therefore, typeof x when x is null evaluates to " object " .

So on line 2, the value printed is:

" object "

This matches option A.

The incorrect options are:

B. " undefined " : would be typeof x if x were undefined, not null.

C. " x " : typeof returns a string describing the type of the value, not the variable name.

D. " null " : although intuitive, JavaScript does not return " null " for typeof null; it returns " object " instead.

Therefore, the correct answer is:

Answer: A

JavaScript knowledge / study guide reference concepts:

typeof operator and its return values

Primitive types in JavaScript (null, undefined, number, string, boolean, symbol, bigint)

Historical behavior: typeof null returning " object "

Difference between null and undefined in JavaScript

document.querySelector( ' #row-as ' ) returns the single element with id row-as.

That element has a classList property with add, remove, etc.

Correct usage:

document.querySelector( ' #row-as ' ).classList.add( ' priority-account ' );

Why others are wrong:

A: querySelectorAll returns a NodeList, not a single element, so it does not have a classList property.

C: DOM elements do not have a classes array or push; they have classList.

D: document.getElementById( ' row-as ' ) is fine to get the element, but there is no addClass method in standard DOM; that’s a jQuery-style API, not vanilla JS.