JavaScript Classes

Defining Classes

class Player {
  constructor(name, dob) {
    this.name = name;
    this.dob = dob;
    this.score = 0;
  }

  addPoints(points) {
    this.score += points;
  }

  getAge() {
    return Math.floor((Date.now() - this.dob.getTime()) / (365 * 86400 * 1000));
  }
}

Instantiation

const player = new Player("Brendan Eich", new Date("July 4, 1961"));
console.log(player instanceof Player);
console.log(player.name);
console.log(player.getAge());
console.log(player.score);
player.addPoints(42);
console.log(player.score);

Inheritance

class Person {
  constructor(name, dob) {
    this.name = name;
    this.dob = dob;
  }

  getAge() {
    return Math.floor((Date.now() - this.dob.getTime()) / (365 * 86400 * 1000));
  }
}

class Player extends Person {
  // Field declaration syntax
  score = 0;

  addPoints(points) {
    this.score += points;
  }
}

const player = new Player("Brendan Eich", new Date("July 4, 1961"));
console.log(player instanceof Person);
console.log(player instanceof Player);
console.log(player.name);
console.log(player.getAge());
console.log(player.score);
player.addPoints(42);
console.log(player.score);