IETF公布了新的HTTP状态码-103， 总结一下就是提前预加载(css、js)文档，提升用户的访问速度。
Summary: a new status code that lets the server send headers early, before the main headers. This helps with optimisations like preloading. Example from the document:
HTTP/1.1 Early Hints
Link: </main.css>; rel=preload; as=style HTTP/1.1 Early Hints
Link: </style.css>; rel=preload; as=style
Link: </script.js>; rel=preload; as=script HTTP/1.1 OK
Date: Fri, May :: GMT
Content-Length:
Content-Type: text/html; charset=utf-
Link: </main.css>; rel=preload; as=style
Link: </newstyle.css>; rel=preload; as=style
Link: </script.js>; rel=preload; as=script
The client can start preloading the CSS and JavaScript before the main headers arrive. This is a nice optimisation.
There are various security risks with sending multiple headers to non-conforming clients hence: “Therefore, a server might refrain from sending Early Hints over HTTP/1.1 unless the client is known to handle informational responses correctly.”
在头部信息到达之前，用户可以开始预加载CSS和JavaScript文件，这是一个很好的优化。
因此，向不合格的客户机发送多个标头存在各种各样的安全风险:“因此，如果客户不知道正确处理信息响应，服务器可能会避免发送HTTP / 1.1的早期提示。”