CIW JavaScript Specialist 3

Question 1

What is a closure in JavaScript?

Accepted Answer

A function that retains access to its outer scope even after the outer function returns

Answer

A closure is a function that remembers variables from its enclosing scope even after that scope has finished executing.

Question 2

Which method is used to attach an event handler to an HTML element in modern JavaScript?

Accepted Answer

addEventListener()

Answer

addEventListener() is the standard DOM method to register an event handler on a specified element for a given event type.

Question 3

What does JSON.stringify() do?

Accepted Answer

Converts a JavaScript value into a JSON-formatted string

Answer

JSON.stringify() serializes a JavaScript object or value into a JSON string representation.

Question 4

Which JavaScript keyword declares a block-scoped variable that cannot be reassigned?

Accepted Answer

const

Answer

const declares a block-scoped variable whose binding cannot be reassigned after initialization.

Question 5

What is the purpose of the Promise.all() method?

Accepted Answer

Returns a promise that resolves when all provided promises resolve, or rejects on first rejection

Answer

Promise.all() takes an iterable of promises and returns a single promise that fulfills when all input promises fulfill, or rejects if any one rejects.

CIW - Certified Internet Web Professional Practice Test

CIW - Certified Internet Web Professional Practice Test

CIW JavaScript Specialist 3