SOURCE

function People(name, age){
	this.name = name
    this.age = age
}

People.prototype.say=function(name, age){
	console.log("my name is " + name+" and i am " + age)
}

let child=new People()
child.say("bruce", 23) //my name is bruce and i am 23
child.__proto__.say("bruce", 23) //和上面效果一样，不过时调用了__proto__