Free Salesforce Certified JavaScript Developer (JS-Dev-101) Practice Questions

The correct answers are C and D .

The statement:

const arr = Array(5).fill(0);

creates an array with 5 elements , and every element is filled with the value 0.

So the array becomes:

[0, 0, 0, 0, 0]

A professional test should verify both important expectations:

arr.length === 5

and:

each element === 0

Option C is correct because it checks every element in the array:

arr.forEach(e = > console.assert(e === 0));

This confirms that each array element was filled with 0.

Option D is correct because it checks the array length:

console.assert(arr.length === 5);

This confirms that the array contains exactly five elements.

Option A is incorrect because the array length is not 0; it is 5.

Option B is incorrect for two reasons. First, arr[5] is outside the valid index range. The valid indexes are:

0, 1, 2, 3, 4

So:

arr[5]

returns:

undefined

Second, arr.length === 0 is false because the length is 5.

Therefore, the verified answers are C and D .