up.protocol
X-Up-Fail-Context
HTTP header
This feature is experimental. Please share your experiences so we know what to keep or change.
This request header contains the context of the layer that Unpoly updates when the server sends an error response, serialized as JSON.
An error response has a status code other than 2xx, but still contains HTML.
Server-side code is free to render different HTML for different contexts.
Example
X-Up-Fail-Context: { "lives": 3 }