prototype chain

protortpe.js

function Animal(age) {
  if (age) { this.age = age; }
    
  // 这个name 不会影响 Dog 或者V, 只会影响new Animal的人
  this.name= "One Animal"
}

Animal.prototype.age = 1;
Animal.prototype.name= "One Animal"; // 优先级 P3


function Dog(name) {
    if (name) { this.name = name; }
}

Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;
Dog.prototype.name  = "Bubbles"; // 优先级 P2

var v = new Dog('Vincent'); // Vincent 优先级 P1
console.log(v.name); // Vincent
console.log(v)