FetchObserver (for a single fetch)

[annevk]

In #447 (comment) @jakearchibald sketched some APIs based on @stuartpb's work which @bakulf then implemented:

• https://developer.mozilla.org/en-US/docs/Web/API/FetchObserver
• https://dxr.mozilla.org/mozilla-central/source/dom/webidl/FetchObserver.webidl
• https://dxr.mozilla.org/mozilla-central/source/dom/webidl/Request.webidl#59

That issue got closed after we landed a subset of that API in Fetch (you can finally abort a fetch). Let's discuss the remainder here (though not priorities, that's #436).

cc @wanderview

[glococo]

Hi,
I found no way of observing the progress on Upload fetch()

var garbage = new Float64Array(new ArrayBuffer(104856))
for (let i=0; i<garbage.length; i++) garbage[i] = Math.random()
var gArray = []
for (let i=0; i<100; i++) gArray.push(garbage);
var gBlob = new Blob(gArray) //10MB

var controller = new FetchController(); // FF55 or AbortController() in Firefox58
var signal = controller.signal;
fetch( "/?action=upload",{ signal, observe(observer) { observer.onresponseprogress=e=>console.log(e);observer.onrequestprogress=e=>console.log(e);observer.onstatechange=n=>console.log(observer.state) }, method:"POST", body:gBlob } )

The only working observer is "state" ( Firefox 55/58 Ubuntu)

[jakearchibald]

The OP reflects the current status. My priorities right now are fetch abort + service worker & background fetch.

[jakearchibald]

Some thoughts on observing H2 push promises https://gist.github.com/slightlyoff/18dc42ae00768c23fbc4c5097400adfb#gistcomment-2227534.

[Cap32]

https://developer.mozilla.org/en-US/docs/Web/API/FetchObserver

This link is 404

[wanderview]

Yeah, I think we removed it from MDN when it became apparent the spec was not immediately moving forward.

[rektide]

Both #51 and #65 are related.

I would love to see this feature added. It would enable some very interesting new reactive models that mesh well with existing HTTP-centric web-systems. Using websocket & SSE is un-ideal in that messaging done there isn't inherently resource-oriented, unlike Push support.

[RikkiGibson]

FetchObserver would enable us to give users a good experience with file uploads without falling back to XMLHttpRequest. Would really like to see it happen.

[annevk]

@RikkiGibson I noticed you're working for Microsoft (not that this is a requirement by all means, but having an employer that supports standards development definitely helps). I don't know how much you're into standards and work with the Edge team, but if you have some time you could help make this happen. We basically need to formalize the proposal and work on tests. There's ample implementer interest already.