javascript 访问 iframe 跨域
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Accessing Iframe Cross Origin
提问by Sanoj Sen
I have an HTML and an iframe inside it. when I try to access iframe contents it shows error like this.
我在里面有一个 HTML 和一个 iframe。当我尝试访问 iframe 内容时，它会显示这样的错误。
" Uncaught DOMException: Blocked a frame with origin "http://parattapayyan.surge.sh" from accessing a cross-origin frame.
at http://parattapayyan.surge.sh/test.html:14:24
(anonymous) @ test.html:14 "
how some chat companies like "intercom" and etc, accessing iframe from external server and components inside iframe..?
一些聊天公司（如“对讲机”等）如何从外部服务器和 iframe 内的组件访问 iframe ..？
回答by Sanoj Sen
When Site A tries to fetch content from Site B in a frame, by default, Site B's pages are not accessible due to security reasons(Read this :: https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy); But using the Access-Control-Allow-Origin header site B can give cross-origin access to specific requesting origins.
当站点 A 尝试在框架中从站点 B 获取内容时，默认情况下，由于安全原因，站点 B 的页面不可访问（阅读此内容 :: https://developer.mozilla.org/en-US/docs/Web/安全/同源策略）；但是使用 Access-Control-Allow-Origin 标头站点 B 可以提供对特定请求源的跨源访问。
Site B can serve its pages to Site A with the following response header:
站点 B 可以使用以下响应标头向站点 A 提供其页面：
Access-Control-Allow-Origin: http://www.siteA.com
Without site B doing this, you won't be able to access site A in a frame.
如果站点 B 不这样做，您将无法在框架中访问站点 A。
