Aff doesn't fail when running on Node

[beckyconning]

The following program outputs [Log] onerror@file:///Users/beckyconning/Documents/purescript-sketchpad/index.js:9693:24 (index.js, line 1302) in a browser but is silent in Node.

It appears print is never called.

module Main where

import Prelude
import Debug.Trace

import Control.Monad.Aff
import Control.Monad.Eff.Console
import Data.Foreign
import Network.HTTP.Affjax

main = runAff print (print <<< show <<< _.status) $ (get "ajsdlfa" :: Affjax _ Foreign)

[stkb]

Have run into this issue too, and it's caused by the underlying xmlhttprequest module, which to be blunt, doesn't work very well. It doesn't support things like the onerror event (the cause of this issue) and would just cause my program to hang in the case of a redirect. There are forks of xmlhttprequest that have fixed various things but with issues and PR's piling up, development on the module seems to have stopped.

I went looking for a possible replacement and xhr2 seems to be a good one. I tried using it in my app instead of xmlhttprequest (with a one-line change in Affjax.js) and everything is working fine so far.

[paf31]

Perhaps purescript-node-http would be a good base for a Node HTTP client backend?

[stkb]

@paf31 Thanks for that; I'd also been looking for a PS library for a lightweight http server. Though for an http client, I like the Aff-style API that Affjax supplies, as well as being able to use the same API in both Node and the web browser.

[jdegoes]

PRs welcome! 😀 External dependencies should add minimal overhead to the library and be reflected in bower dependencies.

[stkb]

@jdegoes Thanks will submit a PR soon :) Am just checking everything works my end

[paf31]

Perhaps it would make sense to break a Node backend out into its own library, if dependencies are a concern. Creating an abstract backend should be straightforward enough, right? Something like type Backend eff = forall req res. (Requestable req, Respondable res) => req -> Affjax eff res.

[jdegoes]

I'm definitely open to feedback. I think a lot of people may run both node and browser tests in the same code base and want an Ajax library that does both; right now we sort of have node support in there but not for error cases.

[beckyconning]

Personally one of the biggest attractions I have to Javascript and PureScript is that DSLs / libraries / patterns can be shared between backend services and clients. I'd prefer to address this inside of Affjax rather than having different modules for dealing with HTTP requests depending on the environment.

[beckyconning]

But its the 'DSL' of Affjax that I think that would be valuable to share between the two rather than necessarily the implementation of it.