Modifying arrays in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

How do you add an element to the end of an array in JavaScript?

Use the push() method. For example, arr.push(element) adds element to the end of arr.

beginner

What method removes the last element from an array?

The pop() method removes the last element and returns it. It changes the original array.

beginner

How can you add an element to the beginning of an array?

Use the unshift() method. For example, arr.unshift(element) adds element to the start of arr.

intermediate

What does the splice() method do?

It can add, remove, or replace elements in an array at any position. For example, arr.splice(start, deleteCount, item1, item2) removes deleteCount elements from start and inserts new items.

beginner

How do you change the value of an element at a specific index in an array?

Assign a new value directly using the index. For example, arr[2] = newValue changes the third element to newValue.

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

A push()

B pop()

C shift()

D unshift()

The push() method adds an element to the end of an array.

What does arr.pop() do?

A Adds an element to the end

B Adds an element to the start

C Removes the first element

D Removes the last element

pop() removes and returns the last element of the array.

How do you remove elements from the middle of an array?

A Using <code>slice()</code>

B Using <code>splice()</code>

C Using <code>push()</code>

D Using <code>pop()</code>

splice() can remove elements from any position in the array.

Which method adds elements to the beginning of an array?

A unshift()

B push()

C pop()

D shift()

unshift() adds elements to the start of an array.

How do you change the value of the second element in an array named arr?

A arr.set(2, newValue)

B arr[2] = newValue

C arr[1] = newValue

D arr.change(1, newValue)

Array indexes start at 0, so the second element is at index 1.

Explain how to add and remove elements from both ends of an array in JavaScript.

Think about methods that work at the start and end of the array.

Describe how the splice() method can be used to modify an array.

Consider how you can remove and add items anywhere in the array.