Not Just for Classes

super works in any object method declared with the shorthand syntax method() {}. When a method uses this syntax, JS stores a reference to its " home object " ([[HomeObject]]) which super uses to find the parent's method.

let animal = {
  sayHi() { console.log('I am an animal'); }
};

let rabbit = {
  __proto__: animal,
  sayHi() {
    super.sayHi(); // Calls animal.sayHi()
    console.log('I am also a rabbit');
  }
};

rabbit.sayHi();
// "I am an animal"
// "I am also a rabbit"