Cache control header mdn. The HTTP Permissions-Policy response header provides a mechanism to allow and deny the use of browser features in a document or within any <iframe> elements in the document. The HTTP Set-Cookie response header is used to send a cookie from the server to the user agent, so that the user agent can send it back to the server later. The Rules: Cache-Control This is the most important header in web performance. The browser may store cookies, create new cookies, modify existing ones, and send them back to the same server with later requests. Effective caching eliminates the need for browsers to re-fetch resources that are not modified, reducing bandwidth usage and improving load speed. Cache-Control 通用消息头字段，被用于在 http 请求和响应中，通过指定指令来实现缓存机制。缓存指令是单向的，这意味着在请求中设置的指令，不一定被包含在响应中。 The content behind MDN Web Docs. The response provided by a cache is stale (the content's age exceeds a maximum age set by a Cache-Control header or heuristically chosen lifetime). Most web servers will send Last Modified headers for static assets like Javascript files. The HTTP Access-Control-Expose-Headers response header allows a server to indicate which response headers should be made available to scripts running in the browser in response to a cross-origin request. Seeking a balance between usability and security, developers implement functionality through the headers that can make applications more versatile or secure. 8voxlb, yrtzy, jchp7, lrbi, wt5zg, uhn8r3, tgrgu, ern5f, 3k13x, 5zai,