Why arrays are needed in Javascript - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an array named fruits.

Javascript

const fruits = [1];

Drag options to blanks, or click blank then click option'

A{'apple', 'banana', 'cherry'}

B'apple', 'banana', 'cherry'

C['apple', 'banana', 'cherry']

D(apple, banana, cherry)

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces instead of square brackets

Not using any brackets

Using parentheses instead of brackets

Arrays in JavaScript are created using square brackets []. This lets us store multiple items in one variable.

2fill in blank

medium

Complete the code to access the first fruit in the array.

Javascript

const firstFruit = fruits[1];

Drag options to blanks, or click blank then click option'

A(0)

B[0]

C{0}

D<0>

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets

Using curly braces

Using angle brackets

We use square brackets with the index number to access an item in an array. Indexing starts at 0.

3fill in blank

hard

Fix the error in the code to add a new fruit to the array.

Javascript

fruits[1]('orange');

Drag options to blanks, or click blank then click option'

Apush

Badd

Cappend

Dinsert

Attempts:

3 left

💡 Hint

Common Mistakes

Using add which is not a method

Using append which is not valid in JavaScript

Using insert which does not exist

The push method adds a new item to the end of an array in JavaScript.

4fill in blank

hard

Complete the code to create an array of numbers and get the last number.

Javascript

const numbers = [1, 2, 3, 4, 5];
const lastNumber = numbers[numbers[1] - 1];

Drag options to blanks, or click blank then click option'

A[

B]

C.length

D.size

Attempts:

3 left

💡 Hint

Common Mistakes

Using .size which is not valid for arrays

Using parentheses instead of square brackets

Not subtracting 1 from length

To get the last item, use array[array.length - 1]. length gives the number of items, and we subtract 1 for the last index.

5fill in blank

hard

Fill both blanks to create an array of words, filter words longer than 3 letters, and create a new array with their lengths.

Javascript

const words = ['cat', 'elephant', 'dog', 'bird'];
const longWordsLengths = words
  .filter(word => word[1] 3)
  .map(word => word[2]);

console.log(longWordsLengths);

Drag options to blanks, or click blank then click option'

A.length >

B.length

C[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using comparison without .length

Trying to access word as an array incorrectly

Not logging the array correctly

We filter words with length greater than 3 using word.length > 3. Then we map each word to its length with word.length. Finally, we log the resulting array.