Posts tagged 'tricks'| www.williamjbowman.com
The HTTP Last-Modified response header contains a date and time when the origin server believes the resource was last modified. It is used as a validator in conditional requests (If-Modified-Since or If-Unmodified-Since) to determine if a requested resource is the same as one already stored by the client. It is less accurate than an ETag for determining file contents, but can be used as a fallback mechanism if ETags are unavailable.| MDN Web Docs
The HTTP Access-Control-Allow-Origin response header indicates whether the response can be shared with requesting code from the given origin.| MDN Web Docs
The HTTP Origin request header indicates the origin (scheme, hostname, and port) that caused the request. For example, if a user agent needs to request resources included in a page, or fetched by scripts that it executes, then the origin of the page may be included in the request.| MDN Web Docs
The HTTP If-None-Match request header makes a request conditional. The server returns the requested resource in GET and HEAD methods with a 200 status, only if it doesn't have an ETag matching the ones in the If-None-Match header. For other methods, the request will be processed only if the eventually existing resource's ETag doesn't match any of the values listed.| MDN Web Docs