function Person(name, age, job) {
this.name = name;
this.age = age;
this.job = job;
this.sayName = sayName;
}
function sayName() {
alert(this.name);
}
var person1 = new Person("Nicholas", 19, "Teacher");
var person2 = new Person("Greg", 20, "Doctor"); 
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
What does it mean that a function defined in the global scope in JavaScript can actually only be called by a certain object? - PHP Chinese Q&A - A function defined in the global scope in JavaScript can actually only be called by a certain object. What does it mean? - PHP Chinese website Q&A
Take a look around and learn.
比如你写了一个插件 plugin.js
想让这个插件内的对象可以被使用者调用
根据使用者的环境不同(web-browser node.js等)，你的这些对象需要”附加“在一些父对象上，这样不同的环境下才可以使用（比如浏览器中window这个父对象)