JavaScript: class in ES6

[hon9g]

INDEX

#	title	link
1	Create Class and Object	go
2	Static Property and Static Method	go
3	Getter and Setter	go

[hon9g]

Create Class and Object

• Define Class from Representation

  class Cat {
  
  // Constructors and Properties
  constructor(name, color) {
  this.name = name
  this.color = color
  }
  
  // Methods
  speak() {
  return`${this.name} is Mewwww`
  }
  }

• Create new Instance

  
  var cat = new Cat('Fluffy', 'White')

console.log(cat); // Cat {name: "Fluffy", color: "White"} console.log(cat.speak()); // Fluffy is Mewwww

- `type of` class Cat
```JavaScript
console.log(typeof Cat); // function

• type of instance cat

  console.log(typeof cat); // object

• instanceof

  console.log(cat instanceof Cat);

[hon9g]

Static Property

• Static Property, also called Class Property

  class Cat {
  constructor(name, color) {
  this.name = name
  this.color = color
  }
  Cat.maxHeight = 500; // Static property
  }

Static Method

• Static Method only exist in Class not instances

  class Cat {
  constructor(name, color) {
  this.name = name
  this.color = color
  }
  static feed() {
  console.log('yum yum');
  }
  }

  let cat = new Cat('nabi', 'yellow');

  console.log(Cat.feed());  // yum yum
  console.log(cat.feed());  // Uncaught TypeError: nabi.feed is not a function

[hon9g]

Getter

class Employee {
  constructor(id) {
    this._id = id;
  }
  // This is the getter
  get id() {
    return this._id;
  }
}

let h = new Employee(9999);

• access to method id() like a property

  console.log(h.id); //9999

Setter

class Employee {
  constructor(id) {
    this._id = id;
  }
  get id() {
    return this._id;
  }
  // This is the setter
  set id(value) {
    this._id = value;
  }
}

• re-allocate the value like property

  let h = new Employee(9999);
  h.id = 7777;

  console.log(h.id); //7777