CIW JavaScript Specialist 2

Question 1

Which JavaScript method returns a new array containing only elements that pass a provided test function?

Accepted Answer

filter()

Answer

filter() creates a new array with all elements for which the callback returns a truthy value.

Question 2

What does the 'this' keyword refer to inside an arrow function?

Accepted Answer

The enclosing lexical context

Answer

Arrow functions do not have their own 'this'; they inherit it from the surrounding lexical scope.

Question 3

Which event is fired when the browser has fully loaded the HTML and built the DOM, but before images and stylesheets finish loading?

Accepted Answer

DOMContentLoaded

Answer

DOMContentLoaded fires when the HTML document is fully parsed and the DOM is ready, without waiting for external resources.

Question 4

What is the result of: typeof null in JavaScript?

Accepted Answer

'object'

Answer

typeof null returns 'object' due to a historic bug in JavaScript that was never corrected for backward compatibility.

Question 5

Which Array method executes a reducer function on each element and returns a single accumulated value?

Accepted Answer

reduce()

Answer

reduce() applies a callback function against an accumulator and each element to reduce the array to a single value.

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