I'm trying to setup AngularJS to communicate with a cross-origin resource where the asset host which delivers my template files is on a different domain and therefore the XHR request that angular performs must be cross-domain. I've added the appropriate CORS header to my server for the HTTP request to make this work, but it doesn't seem to work. The problem is that when I inspect the HTTP requests in my browser (chrome) the request sent to the asset file is an OPTIONS request (it should be a GET request).
我不确定这是AngularJS中的一个bug，还是我需要配置一些东西。根据我的理解，XHR包装器不能做出一个OPTIONS HTTP请求，所以看起来就像浏览器在执行GET请求之前试图弄清楚是否“允许”首先下载资产。如果是这种情况，那么我是否需要与资产主机一起设置CORS头(Access-Control-Allow-Origin: http://asset.host…)?
不知怎的，我通过改变来解决它
<add name="Access-Control-Allow-Headers"
value="Origin, X-Requested-With, Content-Type, Accept, Authorization"
/>
to
<add name="Access-Control-Allow-Headers"
value="Origin, Content-Type, Accept, Authorization"
/>
来的有点晚了
如果你正在使用Angular 7(或5/6/7)和PHP作为API，并且仍然得到这个错误，尝试在端点(PHP API)中添加以下头选项。
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: PUT, GET, POST, PUT, OPTIONS, DELETE, PATCH");
header("Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept, Authorization");
注意:只需要Access-Control-Allow-Methods。但是，我在这里粘贴了另外两个Access-Control-Allow-Origin和Access-Control-Allow-Headers，只是因为你需要正确地设置所有这些，以便Angular应用能够正确地与你的API对话。
希望这能帮助到一些人。
欢呼。
不知怎的，我通过改变来解决它
<add name="Access-Control-Allow-Headers"
value="Origin, X-Requested-With, Content-Type, Accept, Authorization"
/>
to
<add name="Access-Control-Allow-Headers"
value="Origin, Content-Type, Accept, Authorization"
/>
OPTIONS请求绝不是AngularJS的错误，这是跨源资源共享标准要求浏览器的行为。请参考此文件:https://developer.mozilla.org/en-US/docs/HTTP_access_control，其中“概述”部分说:
The Cross-Origin Resource Sharing standard works by adding new HTTP
headers that allow servers to describe the set of origins that are
permitted to read that information using a web browser. Additionally,
for HTTP request methods that can cause side-effects on user data (in
particular; for HTTP methods other than GET, or for POST usage with
certain MIME types). The specification mandates that browsers
"preflight" the request, soliciting supported methods from the server
with an HTTP OPTIONS request header, and then, upon "approval" from
the server, sending the actual request with the actual HTTP request
method. Servers can also notify clients whether "credentials"
(including Cookies and HTTP Authentication data) should be sent with
requests.
提供一个适用于所有WWW服务器的通用解决方案是非常困难的，因为设置取决于服务器本身和你打算支持的HTTP动词。我鼓励您阅读这篇优秀的文章(http://www.html5rocks.com/en/tutorials/cors/)，其中有更多关于服务器需要发送的确切头部的详细信息。
