Map method in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new array with each number doubled using the map method.

Javascript

const numbers = [1, 2, 3];
const doubled = numbers.[1](num => num * 2);
console.log(doubled);

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

Afilter

Bmap

CforEach

Dreduce

Attempts:

3 left

💡 Hint

Common Mistakes

Using forEach instead of map, which does not return a new array.

Using filter, which only selects elements but does not transform them.

The map method creates a new array by applying the function to each element.

2fill in blank

medium

Complete the code to convert all names in the array to uppercase using map.

Javascript

const names = ['alice', 'bob', 'carol'];
const upperNames = names.[1](name => name.toUpperCase());
console.log(upperNames);

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

Afilter

Bsort

Cmap

Dslice

Attempts:

3 left

💡 Hint

Common Mistakes

Using filter which removes elements instead of transforming them.

Using sort which changes order but not content.

map applies the function to each element and returns a new array with uppercase names.

3fill in blank

hard

Fix the error in the code to correctly double each number using map.

Javascript

const nums = [4, 5, 6];
const doubled = nums.map(num => num [1] 2);
console.log(doubled);

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

A*

B/

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using + which adds instead of multiplies.

Using - or / which do not double the number.

To double a number, multiply it by 2 using the * operator.

4fill in blank

hard

Fill both blanks to create an array of squares of even numbers only.

Javascript

const nums = [1, 2, 3, 4, 5];
const squares = nums.filter(n => n [1] 2 === 0).[2](n => n * n);
console.log(squares);

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

A%

Bmap

Cfilter

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of % for checking even numbers.

Using filter instead of map to square numbers.

Use % to check even numbers and map to square them.

5fill in blank

hard

Fill all three blanks to create an array of uppercase names longer than 3 letters.

Javascript

const names = ['Ann', 'Beth', 'Cara', 'Dan'];
const result = names.[1](name => name.[2]()).[3](name => name.length > 3);
console.log(result);

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

Amap

BtoUpperCase

Cfilter

DtoLowerCase

Attempts:

3 left

💡 Hint

Common Mistakes

Using toLowerCase instead of toUpperCase.

Using filter before map, which would filter original names.

First map to uppercase, then filter names longer than 3 letters.