JuniorTheoryCommon

What does the program print?

TypeScript

class Animal {
    describe(): string {
        return "animal";
    }
}
class Dog extends Animal {
    override describe(): string {
        return `dog ${super.describe()}`;
    }
}
const pet: Animal = new Dog();
console.log(pet.describe());

dog animal

Expecting the variable's type Animal to pick the method: the type only limits what tsc lets you call, and at run time the object is a Dog, so its describe runs.
Expecting override to remove the base method: super.describe() still reaches the version of Animal, which returns animal.

What would the program print if Dog did not override describe?
What does tsc report if override is written on a method the base class does not have?

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Back to questions

JuniorTheoryCommon

What does the program print?

TypeScript

class Animal {
    describe(): string {
        return "animal";
    }
}
class Dog extends Animal {
    override describe(): string {
        return `dog ${super.describe()}`;
    }
}
const pet: Animal = new Dog();
console.log(pet.describe());

dog animal

Expecting the variable's type Animal to pick the method: the type only limits what tsc lets you call, and at run time the object is a Dog, so its describe runs.
Expecting override to remove the base method: super.describe() still reaches the version of Animal, which returns animal.

What would the program print if Dog did not override describe?
What does tsc report if override is written on a method the base class does not have?

Back to questions Open topic in roadmap →Answer it yourself — Quiz