function Point(x, y) {
  this.x = x;
  this.y = y;
  this.arr = [x, y];
}
Point.prototype.print = function () {
  console.log(`Point:(${this.x},${this.y})`);
};

function ColorPoint(color) {
  this.color = color;
}
// 将子类的prototype改成父类的实例
ColorPoint.prototype = new Point(1, 2);
ColorPoint.prototype.print = function () {
  console.log(`ColorPoint:(${this.x},${this.y}) ${this.color} [${this.arr}]`);
};

const cp = new ColorPoint("red");
cp.print(); // ColorPoint:(1,2) red [1,2]

const cp2 = new ColorPoint("blue");
cp2.x = 233; // 这种操作只是在cp2增加了一个x属性，不会影响cp的x
cp2.arr[0] = 10086; // 这种操作修改了父类的那个实例的arr的值，会影响到cp
cp2.print(); // ColorPoint:(233,2) blue [10086,2]
cp.print(); // ColorPoint:(1,2) red [10086,2]

console.log(cp instanceof Point); // ture
console.log(cp instanceof ColorPoint); // ture
console.log(Point.prototype.isPrototypeOf(cp)); // ture
console.log(ColorPoint.prototype.isPrototypeOf(cp)); // ture