Capitalize and Uncapitalize types in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to capitalize the first letter of the string type.

Typescript

type Capitalized = [1]<'hello'>;

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

AUncapitalize

BUppercase

CCapitalize

DLowercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using Uncapitalize instead of Capitalize.

Using Uppercase which changes all letters, not just the first.

The Capitalize utility type changes the first letter of a string type to uppercase.

2fill in blank

medium

Complete the code to uncapitalize the first letter of the string type.

Typescript

type LowercaseFirst = [1]<'Hello'>;

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

ACapitalize

BLowercase

CUppercase

DUncapitalize

Attempts:

3 left

💡 Hint

Common Mistakes

Using Capitalize instead of Uncapitalize.

Using Lowercase which changes all letters, not just the first.

The Uncapitalize utility type changes the first letter of a string type to lowercase.

3fill in blank

hard

Fix the error in the code to capitalize the first letter of the string type.

Typescript

type FixCap = [1]<'world'>;

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

ACapitalize

Bcapitalize

CUppercase

Duncapitalize

Attempts:

3 left

💡 Hint

Common Mistakes

Writing 'capitalize' with a lowercase c causes an error.

Using 'uncapitalize' which is not a valid utility type.

TypeScript utility types are case-sensitive. The correct type is Capitalize with a capital C.

4fill in blank

hard

Fill both blanks to create a type that capitalizes and then uncapitalizes a string.

Typescript

type Transform = [1]<[2]<'example'>>;

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

ACapitalize

BUncapitalize

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the order of Capitalize and Uncapitalize.

Using the same utility type twice.

This type first uncapitalizes the string, then capitalizes it, effectively normalizing the first letter.

5fill in blank

hard

Fill all three blanks to create a type that uncapitalizes, capitalizes, and then uncapitalizes a string.

Typescript

type ComplexTransform = [1]<[2]<[3]<'Test'>>>;

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

AUncapitalize

BCapitalize

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the order of utility types.

Using lowercase names for utility types.

This type applies Capitalize, then Capitalize again, then Uncapitalize, showing nested transformations.