Why Sorting Matters and How It Unlocks Other Algorithms in DSA Javascript - Test Your Knowledge

Practice - 5 Tasks

1fill in blank

easy

Complete the code to sort the array in ascending order using the built-in method.

DSA Javascript

const numbers = [5, 3, 8, 1];
numbers.sort([1]);
console.log(numbers);

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

A() => a - b

B(a, b) => b - a

C(a, b) => a - b

D() => b - a

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function without parameters causes incorrect sorting.

Using (a, b) => b - a sorts in descending order, not ascending.

The sort method requires a comparison function with two parameters a and b. Returning a - b sorts ascending.

2fill in blank

medium

Complete the code to find the median after sorting the array.

DSA Javascript

const arr = [7, 2, 5, 3];
arr.sort([1]);
const mid = Math.floor(arr.length / 2);
const median = arr.length % 2 !== 0 ? arr[mid] : (arr[mid - 1] + arr[mid]) / 2;
console.log(median);

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

A(a, b) => a - b

B() => a - b

C(a, b) => b - a

D() => b - a

Attempts:

3 left

💡 Hint

Common Mistakes

Sorting descending changes the median calculation.

Not providing a comparison function sorts elements as strings.

Sorting ascending with (a, b) => a - b is needed to find the correct median.

3fill in blank

hard

Fix the error in the code to correctly sort an array of strings by length.

DSA Javascript

const words = ['apple', 'dog', 'banana', 'cat'];
words.sort((a, b) => [1]);
console.log(words);

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

Ab - a

Bb.length - a.length

Ca - b

Da.length - b.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using a - b or b - a compares strings incorrectly.

Sorting descending when ascending is needed.

To sort strings by length ascending, subtract b.length from a.length.

4fill in blank

hard

Fill both blanks to create a sorted array of unique numbers.

DSA Javascript

const nums = [4, 2, 5, 2, 3, 4];
const uniqueSorted = [...new Set(nums)].sort([1]);
console.log(uniqueSorted);

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

A(a, b) => b - a

B(a, b) => a - b

C() => a - b

D() => b - a

Attempts:

3 left

💡 Hint

Common Mistakes

Not using a comparison function sorts numbers as strings.

Using arrow functions without parameters causes errors.

Use (a, b) => a - b to sort numbers ascending after removing duplicates.

5fill in blank

hard

Fill all three blanks to create a sorted array of objects by age, then map to names.

DSA Javascript

const people = [
  { name: 'Alice', age: 30 },
  { name: 'Bob', age: 25 },
  { name: 'Carol', age: 35 }
];
const sortedNames = people.sort((a, b) => [1]).map(person => person.[2]).filter(name => name.length > [3]);
console.log(sortedNames);

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

Aa.age - b.age

Bname

C3

Db.age - a.age

Attempts:

3 left

💡 Hint

Common Mistakes

Sorting descending when ascending is needed.

Mapping to wrong property name.

Filtering with incorrect length value.

Sort ascending by age with a.age - b.age, map to 'name', and filter names longer than 3 characters.