TS2689

error TS2689: Cannot extend an interface ‘Animal’. Did you mean ‘implements’?

Broken Code ❌

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interface Animal {
  name: string;
}

class Dog extends Animal {
  name = 'Default Dog';
}

Fixed Code ✔️

The TypeScript compiler tells us already the solution: When implementing an interface, we have to use implements. If we inherit from classes, we use extends.

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class Dog extends Animal {
  protected makeNoise(): string {
    return 'Woof!';
  }
}