Bad:

Good:

  constructor(age) {
    this.age = age;
  }
  move() { /* ... */ }
}
class Mammal extends Animal {
  constructor(age, furColor) {
    super(age);
    this.furColor = furColor;
  }
  liveBirth() { /* ... */ }
}
class Human extends Mammal {
  constructor(age, furColor, languageSpoken) {
    super(age, furColor);
    this.languageSpoken = languageSpoken;
  }
  speak() { /* ... */ }
}

Bad:

Good:

    this.make = make;
    this.model = model;
    this.color = color;
  }
  setMake(make) {
    this.make = make;
    // NOTE: Returning this for chaining
    return this;
  }
  setModel(model) {
    this.model = model;
    // NOTE: Returning this for chaining
    return this;
  }
  setColor(color) {
    this.color = color;
    // NOTE: Returning this for chaining
    return this;
  }
  save() {
    console.log(this.make, this.model, this.color);
    // NOTE: Returning this for chaining
}
const car = new Car('Ford','F-150','red')
  .setColor('pink')
  .save();

You might be wondering then, “when should I use inheritance?” It
depends on your problem at hand, but this is a decent list of when inheritance
makes more sense than composition:

1. Your inheritance represents an “is-a” relationship and not a “has-a”
   relationship (Human->Animal vs. User->UserDetails).
2. You can reuse code from the base classes (Humans can move like all animals).
3. You want to make global changes to derived classes by changing a base class.
   (Change the caloric expenditure of all animals when they move).

Bad:

class EmployeeTaxData {
  constructor(ssn, salary) {
    this.ssn = ssn;
    this.salary = salary;
  }
  // ...
}
class Employee {
  constructor(name, email) {
    this.name = name;
    this.email = email;
  }
  setTaxData(ssn, salary) {
    this.taxData = new EmployeeTaxData(ssn, salary);
  }
  // ...
}