Declaring functions and classes in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function named greet that returns a string.

Typescript

function greet() : [1] {
  return "Hello!";
}

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

Astring

Bnumber

Cboolean

Dvoid

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'void' as return type when the function actually returns a string.

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

The function greet returns a string, so the return type should be string.

2fill in blank

medium

Complete the code to declare a class named Person with a constructor that takes a name parameter.

Typescript

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

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

AfullName

Bage

CpersonName

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different parameter name that does not match the assignment.

Forgetting to declare the parameter in the constructor.

The constructor parameter should be named name to match the property assignment this.name = name;.

3fill in blank

hard

Fix the error in the method declaration inside the class Calculator.

Typescript

class Calculator {
  add(a: number, b: number) : [1] {
    return a + b;
  }
}

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

Avoid

Bstring

Cnumber

Dboolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'void' which means no return value.

Using 'string' or 'boolean' which do not match the returned value.

The add method returns the sum of two numbers, so its return type should be number.

4fill in blank

hard

Fill both blanks to declare a class Animal with a method makeSound that returns a string.

Typescript

class [1] {
  [2]() : string {
    return "Some sound";
  }
}

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

AAnimal

BmakeSound

Csound

Dnoise

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect class or method names.

Forgetting to specify the return type.

The class name is Animal and the method name is makeSound which returns a string.

5fill in blank

hard

Fill all three blanks to declare a class Rectangle with a constructor and a method area that returns the area as a number.

Typescript

class [1] {
  width: number;
  height: number;
  constructor([2]: number, [3]: number) {
    this.width = width;
    this.height = height;
  }
  area() : number {
    return this.width * this.height;
  }
}

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

ARectangle

Bwidth

Cheight

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong parameter names that do not match the properties.

Using a class name that does not fit the context.

The class is named Rectangle. The constructor parameters are width and height to match the properties.