JavaScript adds properties and methods to objects

JavaScript can define properties and methods when defining a class, or dynamically add properties and methods after creating an object.

Dynamic addition of properties and methods is difficult to achieve in other object-oriented programming languages (C++, JavaScript, etc.), which is a reflection of the flexibility of JavaScript.

Create an object based on the Person class and add properties and methods to it: // Define class

<script>// 定义类
function Person(name,sex) {
    this.name=name;  // 定义一个属性 name
    this.sex=sex;  // 定义一个属性 sex
    this.say=function(){  // 定义一个方法 say()
        return "嗨！大家好，我的名字是 " + this.name + " ，性别是 " + this.sex + " 。";
    }
}

// 创建对象
var zhangsan=new Person("张三","男");
zhangsan.say();

// 动态添加属性和方法
zhangsan.tel="029-81892332";
zhangsan.run=function(){
    return  " 我跑得很快！ ";
}

// 弹出警告框
alert("姓名："+zhangsan.name);
alert("姓别："+zhangsan.sex);
alert(zhangsan.say());
alert("电话："+zhangsan.tel);
alert(zhangsan.run());</script>

Continuing Learning

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<!DOCTYPE HTML>
<html>
<head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 <title>无标题文档</title>
 <script>// 定义类
 function Person(name,sex) {
 this.name=name; // 定义一个属性 name
 this.sex=sex; // 定义一个属性 sex
 this.say=function(){ // 定义一个方法 say()
 return "嗨！大家好，我的名字是 " + this.name + " ，性别是 " + this.sex + " 。";
 }
 }
 // 创建对象
 var zhangsan=new Person("张三","男");
 zhangsan.say();
 // 动态添加属性和方法
 zhangsan.tel="029-81892332";
 zhangsan.run=function(){
 return " 我跑得很快！ ";
 }
 // 弹出警告框
 alert("姓名："+zhangsan.name);
 alert("姓别："+zhangsan.sex);
 alert(zhangsan.say());
 alert("电话："+zhangsan.tel);
 alert(zhangsan.run());</script>
</head>
<body>
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