B站后盾人视频javascript笔记

JS的原型和基础

https://www.bilibili.com/video/BV17J411y7XZ?p=5

5 函数拥有多个长辈

function User(){}

console.dir(User);

User.prototype.show = function() {
  console.log("周蹲人");
};
let hd = new User();

hd.show();
console.log(User.prototype == hd.__proto__);

 

 6、原型关系详解与属性继承实例

静态方法使用的是__proto__的原型链，实例方法使用的prototype的原型链

let hd = new Object();
hd.name = "后盾人";

Object.prototype.show = function(){
  console.log("hodunren.com");  
};
//hd.show();
function User(){}
//console.dir(User);
//console.log(User.prototype.__proto__ == User.__proto__.__proto__);
console.dir(Object.prototype.__proto__);
let xj = new User();
xj.show();

User.show();

 

 7、系统构造函数的原型体现

let hd = {};//Object
console.log(hd.__proto__ == Object.prototype);

Array.prototype.show = function(){
    console.log('后盾人');
}
let arr = [];//new Array
console.log(arr.__proto__ == Array.prototype);
arr.show();

let str = "";//new String
console.log(str.__proto__ == String.prototype);

let bool = true;
console.log(bool.__proto__ == Boolean.prototype);

let reg = /a/i;//new RegExp
console.log(reg.__proto__ == RegExp.prototype);

8、自定义对象的原型设置

let hd = {name:"hd"};
let parent = {
    name : "parent",
    show() {
        console.log("parent method:" + this.name);
    }         
};

Object.setPrototypeOf(hd, parent);
//hd.show();
//parent.show();
console.log(Object.getPrototypeOf(hd));

 

10、给我一个对象，还你一个世界

function User(name){
  this.name = name;
  this.show= function() {
    console.log(this.name);
  }
}

  let hd = new User("后蹲人");
  console.log(hd);
  function createByObject(obj, ...args) {

    const constructor = Object.getPrototypeOf(obj).constructor;
    return new constructor(...args);
  }

  let xj = createByObject(hd,"向军");
  xj.show();

 

 

 

 

 

 

 

 

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