Web Programming JavaScript Programming 2

Question 1

What is a JavaScript Promise used for?

Accepted Answer

Handling asynchronous operations

Answer

A Promise represents the eventual completion or failure of an asynchronous operation and allows you to attach callbacks via .then() and .catch().

Question 2

Which array method creates a new array with elements that pass a test function?

Accepted Answer

filter()

Answer

The filter() method creates a new array containing only elements for which the provided callback function returns a truthy value.

Question 3

What does the arrow function syntax `const add = (a, b) => a + b` return?

Accepted Answer

The sum of a and b

Answer

This arrow function with a concise body (no braces) implicitly returns the expression a + b, which is the sum of the two parameters.

Question 4

What is the purpose of the async/await keywords in JavaScript?

Accepted Answer

To write asynchronous code in a synchronous style

Answer

async/await is syntactic sugar over Promises that allows writing asynchronous code in a linear, synchronous-looking style, improving readability.

Question 5

Which JavaScript event listener method attaches an event handler to an element?

Accepted Answer

addEventListener()

Answer

addEventListener() attaches an event handler function to an element for a specified event type, supporting multiple handlers per event.

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