Sorting Stability and When to Use Which Sort in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to sort the array of objects by age using a stable sort.

DSA Javascript

people.sort((a, b) => a.age [1] b.age);

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

A-

B+

C===

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using comparison operators like '>' or '===' which do not return the expected numeric value for sort.

The subtraction operator - returns a negative, zero, or positive number which is required for the sort callback to work correctly and maintain stability.

2fill in blank

medium

Complete the code to keep the original order of items with the same score using a stable sort.

DSA Javascript

items.sort((a, b) => a.score [1] b.score);

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

A-

B===

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using comparison operators that return boolean values instead of numbers.

Subtracting b.score from a.score returns a number that the sort method uses to order items, preserving stability for equal scores.

3fill in blank

hard

Fix the error in the code to ensure stable sorting by name when ages are equal.

DSA Javascript

people.sort((a, b) => a.age - b.age || a.name [1] b.name);

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

A===

B>

C-

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction on strings which causes NaN and breaks sorting.

When ages are equal, comparing names with < returns a boolean which can be converted to a number to decide order. This helps keep the sort stable by name.

4fill in blank

hard

Fill both blanks to create a dictionary of word lengths for words longer than 3 characters.

DSA Javascript

{ [1]: [2] for word in words if word.length > 3 }

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

Aword

Blen(word)

Cword.length

Dword.upper()

Attempts:

3 left

💡 Hint

Common Mistakes

Using Python's len() function instead of JavaScript's length property.

The key is the word itself, and the value is its length using word.length in JavaScript.

5fill in blank

hard

Fill all three blanks to filter and map an array of numbers to their squares if they are even.

DSA Javascript

const result = numbers.filter(n => n [1] 2 === 0).map(n => n [2] [3]);

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

A%

B**

C2

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect operators for checking even numbers or squaring.

Use % to check even numbers, then n ** 2 to get the square.