Array type annotation syntax in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an array of numbers using the shorthand syntax.

Typescript

let numbers: number[1] = [1, 2, 3];

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

A()

B{}

C[]

D<>

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces instead of square brackets.

Using angle brackets which are for generics, not array shorthand.

The correct syntax to declare an array of numbers is number[].

2fill in blank

medium

Complete the code to declare an array of strings using the generic Array syntax.

Typescript

let fruits: Array[1] = ['apple', 'banana', 'cherry'];

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

A{}

B<string>

C[]

D()

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of angle brackets.

Using square brackets which is shorthand, not generic syntax.

The generic syntax for an array of strings is Array<string>.

3fill in blank

hard

Fix the error in the array type annotation syntax.

Typescript

let scores: number[1] = [10, 20, 30];

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

A[]

B<>

C{}

D()

Attempts:

3 left

💡 Hint

Common Mistakes

Using angle brackets which are for generics, not shorthand arrays.

Using parentheses or curly braces which are invalid here.

The correct array type annotation uses square brackets [] after the type.

4fill in blank

hard

Fill both blanks to declare an array of booleans using generic syntax.

Typescript

let flags: Array[1] = [2];

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

A<boolean>

B[true, false, true]

C[false, true]

D<string>

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong type inside angle brackets.

Using a string array instead of boolean array.

The generic array syntax is Array<boolean> and the array value is [true, false, true].

5fill in blank

hard

Fill all three blanks to declare an array of objects with a specific type.

Typescript

type Person = { name: string, age: number };
let people: [1] = [2];

people.push([3]);

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

AArray<Person>

B[{ name: 'Alice', age: 30 }]

C{ name: 'Bob', age: 25 }

DPerson[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using shorthand array syntax instead of generic syntax for the type.

Pushing a non-object or missing required properties.

The array type can be declared as Array<Person>. The initial array is [{ name: 'Alice', age: 30 }]. To add a new person, use an object like { name: 'Bob', age: 25 }.