# 2.4 關於跨網域

## 關於跨網域

預設上都是禁止跨網域取得資料的，若跨網域取得資料，會發現如下錯誤：

![](/files/-M5kmOE6J2op2uYsHA9l)

### CORS (跨網域資源共享)

CORS = **C**ross-**O**rigin **R**esource **S**haring

解決方式，設定 **`Access-Control-Allow-Origin`** 以及 **`Access-Control-Allow-Methods`** 這兩個表頭資訊。如果有允許其它表頭資訊的話，可再設定 **`Access-Control-Allow-Headers`** 。

第一種設定方式，以 Apache 的 **`.htaccess`** 檔為例：

```bash
Header add Access-Control-Allow-Origin "*"
Header add Access-Control-Allow-Methods "*"

# 如果有額外帶其它表頭資訊的話，也可以設定允許的表頭資訊
Header add Access-Control-Allow-Headers "API-Key"
```

第二種設定方式，以 PHP 程式個別檔案去設定：

```php
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: *");

// 如果有額外帶其它表頭資訊的話，也可以設定允許的表頭資訊
header("Access-Control-Allow-Headers: API-Key");
```


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