JS prototype trap

js Prototype properties are real-time

What is real-time
Such as ：

function Person(){
	this.name = "mike";
}

var p1 = new Person();
p1.name; // mike
Person.prototype.age = 12;
p1.age; // 12  Real time hanging on new properties 

Not reliable constructor

function Person(){
	this.name = "mike";
}
Person.prototype.say = function(){
	return this.name;
}
var p1 = new Person();
p1.say(); // "mike"
p1.constructor; 
/*
ƒ Person(){
	this.name = "mike";
}
*/
Person.prototype = {
	sex: 'male'
}

p1.say();//"mike"
var p2 = new Person();
p2.say();// error;
p2.constructor; // ƒ Object() { [native code] }

Changed the Person.prototype constructor It's also changing
But the old p1 adopt __proto__ You can still visit say

How to avoid constructor The loss of

Changing prototype After that, please constructor Point back to the original constructor

function Person(){}
Person.prototype = {};
Person.prototype.constructor = Person;