SOURCE

class Animal {
    speak() {
        return this;
    }
    static eat() {
        return this;
    }
}

let obj = new Animal();
console.log(JSON.stringify(obj.speak()))
let speak = obj.speak;
console.log(JSON.stringify(speak()))


console.log(JSON.stringify(Animal.eat()))
let eat = Animal.eat;
eat();
console.log(JSON.stringify(eat()))



// 静态方法 static 关键字用来定义一个类的一个静态方法。
// 调用静态方法不需要实例化该类，但不能通过一个类实例调用静态方法。
// 静态方法通常用户为一个应用程序创建工具函数。

class Point {
    constructor(x, y) {
        this.x = x;
        this.y = y;
    }
    static distance(a, b) {
        
        const dx = a.x - b.y;
        const dy = a.y - b.y;

        return Math.hypot(dx, dy);
    }
}

const p1 = new Point(5, 5)
const p2 = new Point(10, 10);

console.log(Point.distance(p1, p2));



class Rectangle {
    constructor(height, width) {
        this.height = height;
        this.width = width;
    }
    get area() {
        return this.calcArea()
    }
    calcArea() {
        console.log(this.width)
        return this.height * this.width;
    }
}

const square = new Rectangle(10, 100);

console.log(square.area);