Speculation-Rules
Response headers
Gives the browser rules for which URLs to prefetch or prerender ahead of time.
| On the wire | Speculation-Rules: … |
|---|---|
| Category | Response headers |
Headers the server attaches when it answers.
How to read this
- The first digit of a status code carries the meaning: 4 means the request, 5 means the server.
- 404 means "not there"; 403 means "there, but not for you". Swapping them makes debugging slower.
- Header names are case-insensitive — Content-Type and content-type are the same header.
- Caching and CORS problems usually come down to one header line, visible in the browser’s network tab.
Frequently asked questions
Q. What does HTTP Speculation-Rules mean?
Gives the browser rules for which URLs to prefetch or prerender ahead of time.
Q. What does Speculation-Rules look like on the wire?
It travels as Speculation-Rules: …
Q. Where does Speculation-Rules appear?
In response headers.
Q. What group does Speculation-Rules belong to?
The response headers group; the rest of that group is listed further down.