* 形参的默认值----当不传入参数的时候默认使用形参里的默认值
function Point(x = 1,y = 2) {
this.x = x;
this.y = y;
}
//定义一个点的坐标的构造函数
function Point(x = 0, y = 0){
this.x = x;
this.y = y;
}
let point = new Point(23, 35);
console.log(point);
let point1 = new Point();
console.log(point1);
