Quiz

JavaScript Array Methods Quiz

8 questions on array methods: push, map, filter, reduce, and more. Find out how confidently you use them.

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Question 1 of 8

Which method adds an element to the end of an array?

push()✓✗ pop()✓✗ shift()✓✗ unshift()✓✗

Question 2 of 8

What does [1,2,3].map(n => n * 2) return?

[1,2,3]✓✗ 6✓✗ [2,4,6]✓✗ undefined✓✗

Question 3 of 8

Which method returns a new array with only the elements that pass a test?

map()✓✗ filter()✓✗ forEach()✓✗ find()✓✗

Question 4 of 8

What does arr.pop() do?

Adds an element to the start✓✗ Removes and returns the last element✓✗ Removes the first element✓✗ Sorts the array✓✗

Question 5 of 8

How do you check if a variable is an array?

typeof arr === "array"✓✗ arr.isArray()✓✗ Array.isArray(arr)✓✗ arr instanceof Object✓✗

Question 6 of 8

What does [1,2,3].reduce((sum, n) => sum + n, 0) do?

Returns [1,2,3]✓✗ Returns 6✓✗ Returns 3✓✗ Returns undefined✓✗

Question 7 of 8

Which method finds the first element that satisfies a condition?

find()✓✗ findIndex()✓✗ includes()✓✗ some()✓✗

Question 8 of 8

What does arr.splice(1, 2) do?

Adds 2 elements at index 1✓✗ Removes 2 elements starting at index 1✓✗ Copies part of the array✓✗ Does nothing without a 3rd argument✓✗

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