Method overriding with types in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to override the method in the subclass.

Typescript

class Animal {
  speak(): string {
    return "Generic sound";
  }
}

class Dog extends Animal {
  speak(): [1] {
    return "Bark";
  }
}

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

Aboolean

Bstring

Cvoid

Dnumber

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different return type like number or void causes a type error.

The overridden method must have the same return type 'string' as in the base class.

2fill in blank

medium

Complete the code to override the method with a parameter type.

Typescript

class Vehicle {
  move(distance: number): string {
    return `Moved ${distance} meters`;
  }
}

class Car extends Vehicle {
  move([1]): string {
    return `Car moved ${distance} meters`;
  }
}

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Adistance: number

Bdistance: boolean

Cdistance: string

Ddistance

Attempts:

3 left

💡 Hint

Common Mistakes

Changing the parameter type to string or boolean causes a type mismatch.

The parameter type must match the base class method's parameter type 'number'.

3fill in blank

hard

Fix the error in the method override by correcting the return type.

Typescript

class Printer {
  print(): void {
    console.log("Printing...");
  }
}

class ColorPrinter extends Printer {
  print(): [1] {
    console.log("Printing in color...");
  }
}

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

Astring

Bboolean

Cnumber

Dvoid

Attempts:

3 left

💡 Hint

Common Mistakes

Changing the return type to string or number causes a type error.

The overridden method must have the same return type 'void' as the base class method.

4fill in blank

hard

Fill both blanks to correctly override the method with parameter and return types.

Typescript

class Calculator {
  calculate(a: number, b: number): number {
    return a + b;
  }
}

class AdvancedCalculator extends Calculator {
  calculate([1], [2]): number {
    return a * b;
  }
}

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Aa: number

Bb: string

Cb: number

Da: string

Attempts:

3 left

💡 Hint

Common Mistakes

Using string types for parameters causes type errors.

Both parameters must have the same types as in the base class method: 'a: number' and 'b: number'.

5fill in blank

hard

Fill all three blanks to override the method with parameter types and return type.

Typescript

class Logger {
  log(message: string, level: number): [1] {
    return `${level}: ${message}`;
  }
}

class CustomLogger extends Logger {
  log([2], [3]): string {
    return `Level ${level} - ${message}`;
  }
}

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

Astring

Bmessage: string

Clevel: number

Dvoid

Attempts:

3 left

💡 Hint

Common Mistakes

Changing parameter types or return type causes type errors.

The return type and parameter types must match the base class method: return type 'string', parameters 'message: string' and 'level: number'.