Why typed classes matter in Typescript - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a typed class property.

Typescript

class Person {
  name: [1];
  constructor(name: string) {
    this.name = name;
  }
}

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

Anumber

Bstring

Cboolean

Dany

Attempts:

3 left

💡 Hint

Common Mistakes

Using number or boolean for a name property.

Using any which loses type safety.

The name property should be typed as string because it holds text.

2fill in blank

medium

Complete the code to add a typed method that returns the person's name.

Typescript

class Person {
  name: string;
  constructor(name: string) {
    this.name = name;
  }

  getName(): [1] {
    return this.name;
  }
}

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

Anumber

Bvoid

Cstring

Dboolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using void as return type when the method returns a value.

Using number or boolean which do not match the returned value.

The method getName returns the name which is a string, so its return type must be string.

3fill in blank

hard

Fix the error in the class by typing the age property correctly.

Typescript

class Person {
  name: string;
  age: [1];
  constructor(name: string, age: number) {
    this.name = name;
    this.age = age;
  }
}

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

Aany

Bboolean

Cstring

Dnumber

Attempts:

3 left

💡 Hint

Common Mistakes

Typing age as string or boolean.

Using any which removes type safety.

The age property should be typed as number because it holds numeric data.

4fill in blank

hard

Fill both blanks to create a typed method that sets the person's age.

Typescript

class Person {
  age: number;
  setAge([1]: [2]) {
    this.age = age;
  }
}

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

Aage

Bstring

Cnumber

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different parameter name than age.

Typing the parameter as string instead of number.

The method parameter should be named age and typed as number to match the property.

5fill in blank

hard

Fill all three blanks to create a typed class with a constructor and a method that returns a greeting.

Typescript

class Person {
  name: [1];
  constructor(name: [2]) {
    this.name = name;
  }
  greet(): [3] {
    return `Hello, ${this.name}!`;
  }
}

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

Astring

Bnumber

Dboolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using number or boolean types for name or return type.

Mismatching types between property and constructor parameter.

The name property and constructor parameter should be typed as string. The greet method returns a string greeting.