class

/*
     1. 通过Class定义类
     2. 在类中通过constructor定义构造方法
     3. 通过new来创建类的实例
     4. 通过extends来实现类的继承
 */

    class Point {
        constructor(x, y) {
            this.x = x;
            this.y = y;
        }
        toString() {
            return this.x + this.y;
        }
    }

    var point = new Point(2,3);
    console.log(point.toString());
/*
    class ColorPoint extends Point {
        constructor(x, y, color) {
            super(x, y);
            this.color = color;
        }

        toString() {
            return this.color + ' ' + super();
        }
    }

    var colorPoint = new Color(3, 4, 'red');
    console.log(colorPoint.toString());
 */