js获取当前域名

获取当前域名可以使用JavaScript的`location`对象。

`location`对象包含了当前 URL 的信息，可以通过它来获取域名。

1. `location.hostname`：获取当前域名，不包含协议和端口号。

2. `location.host`：获取当前域名及端口号，包含协议。

3. `location.href`：获取完整的 URL，包含协议、域名、端口号和路径。

下面将详细介绍如何使用这些属性获取当前域名，并展示一些使用场景和注意事项。

1. 获取当前域名：

```javascript

var domain = location.hostname;

console.log(domain); // 输出当前域名

```

2. 获取当前域名及端口号：

```javascript

var domainWithPort = location.host;

console.log(domainWithPort); // 输出当前域名及端口号

```

3. 获取完整的 URL：

```javascript

var fullUrl = location.href;

console.log(fullUrl); // 输出完整的 URL

```

使用场景：

- 域名白名单：可以在前端代码中获取当前域名，然后与事先定义好的白名单域名进行比较，判断是否允许当前请求。

- 域名相关业务：根据当前域名的不同，可以展示不同的内容或者执行不同的操作，例如多语言切换、广告投放等。

需要注意的是，由于 JavaScript 是在浏览器中执行的，所以获取到的域名是浏览器当前正在访问的域名，而不是你在代码中设置的域名。如果你的网站有多个域名指向同一个服务器，那么获取到的域名是用户输入的域名。

并且，获取域名的 JavaScript 必须在页面加载完毕后才能执行，因为在页面加载过程中，`location`对象可能还未完全初始化。

In JavaScript

you can get the current domain name using the `location` object.

The `location` object contains information about the current URL and can be used to retrieve the domain name.

1. `location.hostname`: Get the current domain name without the protocol and port number.

2. `location.host`: Get the current domain name with the port number

including the protocol.

3. `location.href`: Get the complete URL including the protocol

domain name

port number

and path.

Let's dive into how you can use these properties to get the current domain name

and explore some use cases and considerations.

1. Get the current domain name:

```javascript

var domain = location.hostname;

console.log(domain); // Output the current domain name

```

2. Get the current domain name with the port number:

```javascript

var domainWithPort = location.host;

console.log(domainWithPort); // Output the current domain name with the port number

```

3. Get the complete URL:

```javascript

var fullUrl = location.href;

console.log(fullUrl); // Output the complete URL

```

Use cases:

- Domain whitelist: You can use JavaScript to get the current domain name and compare it with a predefined whitelist to determine whether the current request is allowed.

- Domain-specific business logic: By taking advantage of the current domain name

you can display different content or perform different actions based on the domain

such as language switching

advertising

etc.

It is important to note that JavaScript runs in the browser

so the domain name you get is the one the browser is accessing

not the one you set in your code. If your website has multiple domain names pointing to the same server

the domain name you obtain will be the one entered by the user.

Moreover

the JavaScript code to retrieve the domain name must be executed after the page has finished loading

as the `location` object may not be fully initialized during the page loading process.