javascript - 原型(prototype)中未定义

Question

我更改了人类原型(prototype)，现在检查属性时仍然未定义:

function Human() {
    this.name = "Default Human";
    this.age = "Default Age";
    this.height = 122;
}

function humanExtend() {
    this.address = "Updated Address Sun";
    this.power = "ShowBoat";
}

var banmeet = new Human();
console.log(banmeet.name);

Human.prototype = humanExtend;

var bradPitt = new Human();
console.log(bradPitt.power);

但是我得到了 bradPitt.power 未定义的信息。。

这是为什么？

Answer 1

您应该已被分配 HumanExtend 实例，如下所示 -

function Human() {
    this.name = "Default Human";
    this.age = "Default Age";
    this.height = 122;


}
function humanExtend() {
    this.address = "Updated Address Sun";
    this.power = "ShowBoat";

}

var banmeet = new Human();
console.log(banmeet.name);


//Assign instance of HumanExtend here
Human.prototype = new humanExtend();


var bradPitt = new Human();
console.log(bradPitt.power);