javascript - 通过 this 使用方法访问对象

Question

你能帮我解决这个代码吗？

var mac = {  
    notebook: "macbook",  
    desktop: "imac",  
    get_product: function (kind) {  
        return this.kind;  
    }  
}  

console.log(mac.get_product(notebook)); //ReferenceError: notebook is not defined

我希望“macbook”能够登录控制台。

感谢您的帮助。

Answer 1

所以，这就是你想要做的代码：

var mac = {  
    notebook: "macbook",  
    desktop: "imac",  
    get_product: function (kind) {  
        return this[kind];  
    }  
}  

console.log(mac.get_product('notebook'));

查看您的原始代码：

var mac = {  
    notebook: "macbook",  
    desktop: "imac",  
    get_product: function (kind) {  
        // this.kind means mac.kind. You haven't defined mac.kind.
        // return this.kind;  
        // instead, you want to look up the value of the property defined
        // at kind.

        // [] allow you to dynamically access properties in JavaScript
        // this["<something>"] means "get me the property named <something>
        // but because the contents of [] are determined before the overall
        // expression, this is the same as return this["<something>"];
        // var prop = "<something>";  return this[prop];
        return this[kind];
    }  
}  
// notebook (without quotes) is interpreted as a variable, but there is no
// variable by the name "notebook".
console.log(mac.get_product(notebook));

Answer 2

这有几件事。

1. 没有“笔记本”之类的东西（它是“mac.notebook”），

2. 没有“this.kind”这样的东西（我想你的意思是“this.notebook”）。

   var mac = {  
       notebook: "macbook",  
       desktop: "imac",  
       get_product: function (kind) {  
           return this.notebook;  
       }  
   }  
   
   console.log(mac.get_product(mac.notebook)); 
   

Answer 3

notebook是内部的，mac所以你不能访问它console.log(mac.get_product(notebook));

看看这篇文章：http: //javascriptissexy.com/understand-javascripts-this-with-clarity-and-master-it/

Answer 4

就像get_product函数一样，notebook参数也在变量 mac 中定义 - 所以你需要将它称为mac.notebook.