Optional elements in tuples in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a tuple with an optional second element.

Typescript

let tuple: [number, string[1]];

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

A?

B!

C:

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using a colon or semicolon instead of a question mark.

Forgetting to mark the element as optional.

The question mark ? marks the second element as optional in the tuple.

2fill in blank

medium

Complete the code to create a tuple type where the last element is optional and of type boolean.

Typescript

type MyTuple = [string, number, boolean[1]];

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

A?

B!

C:

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using exclamation mark or colon instead of question mark.

Placing the question mark before the type.

The ? after boolean marks the last element as optional in the tuple type.

3fill in blank

hard

Fix the error in the tuple type declaration to make the second element optional.

Typescript

let data: [string, number[1]];

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

A;

B!

C:

D?

Attempts:

3 left

💡 Hint

Common Mistakes

Using exclamation mark or colon instead of question mark.

Not placing the question mark immediately after the type.

Adding ? after number makes the second element optional.

4fill in blank

hard

Fill both blanks to declare a tuple with an optional second element of type string and an optional third element of type boolean.

Typescript

let tuple: [number, string[1], boolean[2]];

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

A?

B!

C:

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using exclamation marks or colons instead of question marks.

Marking only one element as optional.

Both the second and third elements are optional, so both have ? after their types.

5fill in blank

hard

Fill both blanks to create a tuple type with an optional first element of type string, a required second element of type number, and an optional third element of type boolean.

Typescript

type CustomTuple = [string[1], number, boolean[2]];

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

A?

D!

Attempts:

3 left

💡 Hint

Common Mistakes

Marking the required element as optional.

Using exclamation marks instead of question marks.

The first and third elements are optional, so they have ?. The second element is required, so it has no symbol.