Explicit type annotations in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to explicitly declare the type of the variable age as number.

Typescript

let age: [1] = 25;

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

Aany

Bstring

Cboolean

Dnumber

Attempts:

3 left

💡 Hint

Common Mistakes

Using string type for a numeric value.

Omitting the type annotation.

The variable age is declared with the type number to explicitly specify it holds numeric values.

2fill in blank

medium

Complete the code to explicitly declare the type of the function parameter name as string.

Typescript

function greet(name: [1]) {
  return `Hello, ${name}!`;
}

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

Anumber

Bboolean

Cstring

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Using number type for a text parameter.

Not specifying any type.

The parameter name is explicitly typed as string because it represents text.

3fill in blank

hard

Fix the error by explicitly typing the variable isActive as a boolean.

Typescript

let isActive: [1] = true;

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

Aany

Bboolean

Cstring

Dnumber

Attempts:

3 left

💡 Hint

Common Mistakes

Typing isActive as string or number.

Leaving out the type annotation.

The variable isActive holds a true/false value, so it must be typed as boolean.

4fill in blank

hard

Fill both blanks to explicitly type the array scores as an array of numbers and the variable total as a number.

Typescript

let scores: [1] = [10, 20, 30];
let total: [2] = 60;

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

Anumber[]

Bstring[]

Cnumber

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Typing scores as string[].

Typing total as string or any.

scores is an array of numbers, so its type is number[]. total is a single number, so its type is number.

5fill in blank

hard

Fill all three blanks to explicitly type the object person with name as string, age as number, and isStudent as boolean.

Typescript

let person: { name: [1]; age: [2]; isStudent: [3] } = {
  name: "Alice",
  age: 22,
  isStudent: false
};

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

Astring

Bnumber

Cboolean

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up types for properties.

Using any instead of specific types.

The object person has name as a string, age as a number, and isStudent as a boolean, so the types must match accordingly.