A lot of people have responded "yes", but no one's taught you how yet, so here's some example code that you can paste into your browser's Devtools or Node's REPL:

    class Dog {
      speak() {
        console.log("bark!");
      }
    }
    class Cat {
      speak() {
        console.log("meow!");
      }
    }
    animal = new Dog();
    animal.speak();
    Object.setPrototypeOf(animal, Cat.prototype);
    animal.speak();

This will produce:

    bark!
    meow!