Type annotation on function parameters in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a type annotation for the parameter name as a string.

Typescript

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

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

Aname: string

Bstring name

Cname number

Dname = string

Attempts:

3 left

💡 Hint

Common Mistakes

Using space instead of colon between parameter and type.

Putting the type before the parameter name.

Assigning a value instead of annotating the type.

The correct syntax to annotate a parameter type in TypeScript is name: string.

2fill in blank

medium

Complete the code to add a type annotation for the parameter age as a number.

Typescript

function setAge([1]) {
  console.log(`Age is ${age}`);
}

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

Anumber age

Bage string

Cage = number

Dage: number

Attempts:

3 left

💡 Hint

Common Mistakes

Using space instead of colon.

Putting the type before the parameter name.

Assigning a value instead of annotating the type.

The correct way to annotate a number parameter is age: number.

3fill in blank

hard

Fix the error in the function parameter type annotation for isActive which should be a boolean.

Typescript

function setActive([1]) {
  console.log(`Active status: ${isActive}`);
}

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

AisActive = boolean

BisActive: boolean

Cboolean isActive

DisActive string

Attempts:

3 left

💡 Hint

Common Mistakes

Using space instead of colon.

Putting the type before the parameter name.

Assigning a value instead of annotating the type.

The correct syntax for a boolean parameter is isActive: boolean.

4fill in blank

hard

Fill both blanks to add type annotations for parameters title as string and pages as number.

Typescript

function bookInfo([1], [2]) {
  return `${title} has ${pages} pages.`;
}

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

Atitle: string

Bpages: string

Cpages: number

Dtitle number

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up types for parameters.

Using space instead of colon.

Putting type before parameter name.

The correct annotations are title: string and pages: number.

5fill in blank

hard

Fill all three blanks to add type annotations for parameters firstName and lastName as strings, and age as number.

Typescript

function personInfo([1], [2], [3]) {
  return `${firstName} ${lastName} is ${age} years old.`;
}

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

AfirstName: string

BlastName: string

Cage: number

Dage string

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong types for parameters.

Forgetting colon between parameter and type.

Putting type before parameter name.

The correct annotations are firstName: string, lastName: string, and age: number.