Okay. The initiator in this case is not “link”. I will create a Chromium bug report.
IG: "Used" is complicated. Say I initiate the fetch via XHR (initiator: xmlhttprequest)... how does the UA know when and if the response is "used"? The app could fetch it, sniff the response, and throw it away - we wouldn't know any better. Same for images: the resource is fetched but is inside a hidden div which is never seen by the user - is that "used"? And so on. I wonder if both cases could be adequately handled by simply indicating when a resource is served from the ephemeral cache, which in Chromium is the renderer’s MemoryCache. In general every sub-resource will be retrieved via a network fetch, via an HTTP cache lookup, or via a read from the ephemeral cache. We can then infer that a preload/pre-render object is “used” or not by whether or not it has a corresponding subsequent sub-resource that was retrieved from the ephemeral cache. Does that make any sense? Peter On Aug 12, 2014, at 6:04 PM, Ilya Grigorik <[email protected]> wrote: > > On Tue, Aug 12, 2014 at 2:07 PM, <[email protected]> wrote: > Another hole in the ResourceTiming API is that I can’t tell if objects > requested via LINK rel=subresource were subsequently used by the page. > ResourceTiming API treats preloaded resources the same as regular resources > on that page. Also, there is no indicator that the initiator was a LINK tag. > > Seems like an implementation bug. I think the spec covers this case already: > "If the initiator is an element, on getting, the initiatorType attribute must > return a DOMString with the same value as the localName of that element." > > Hint-initiated fetch should return "link". Yes, it doesn't tell you if it was > subresource or prefetch, but same constraint applies to other elements (and > CSS initiated downloads in particular). I'm not sure if we need to expose > more? > > In summary, there is no way to figure out that preload hints were > successfully used or not. > > "Used" is complicated. Say I initiate the fetch via XHR (initiator: > xmlhttprequest)... how does the UA know when and if the response is "used"? > The app could fetch it, sniff the response, and throw it away - we wouldn't > know any better. Same for images: the resource is fetched but is inside a > hidden div which is never seen by the user - is that "used"? And so on. > > ig
