[Feature Request] Ability to handle network error easier

[MarlBurroW]

Currently, I didn't found any explicit way to handle network error with wretch. Catch network error is very useful on mobile app or desktop app (electron) to give a better feedback to the end user, or trigger some offline stuff if a network issue is detected.

In 1.5.5, I manage network error with this kind of code:

// This call will trigger a `net::ERR_NAME_NOT_RESOLVED`, 
// and the error passed to the `catch()` will be a string containing `Failed to fetch`
wretch(`http://unexisting-server`)
  .post()
  .res(res => {})
  .catch(error => {
    if (!error.response) {
      // Here is the network error handling
    } else {
      // Here is the http error handling
    }
  })

But it's not very straightforward as wretch has accustomed us.

Something like this is probably more "wretch":

wretch("http://unexisting-server")
  .get()
  .networkError(error => { /* ... */ })
  .res(response => /* ... */)
  .catch(error => { /* uncaught errors */ })

I know fetch doesn't give any information about the network error (there is no way to know that the error see above is a net::ERR_NAME_NOT_RESOLVED, but it's good to know at less that is a network error, and have a nice way to handle it.

Possibly related to this: #56

[elbywan]

Currently, I didn't found any explicit way to handle network error with wretch. Catch network error is very useful on mobile app or desktop app (electron) to give a better feedback to the end user, or trigger some offline stuff if a network issue is detected.

NetworkErrors are very browser/platform dependent.

But what I can add is a .fetchError that will only include errors encountered when calling .fetch, which would be roughly equivalent most of the time.

[MarlBurroW]

I know fetch has different low level implementations on each browser, but I guess it works the same on all browsers at the top level of fetch javascript api: Basically, it rejects the promise if it was not able to retrieve a response from the server, maybe with different messages, but it does not matter. The main goal of my request is "have a handler method on the wretch api to know when a true fetch error occurs, and then be able to do different things, without manually check the presence of the response property in the wretch reject handler.

So yes, a .fetchError() handler method sounds good to me !

Thanks for your work

[elbywan]

📦 Version 1.6.0 has just been released with the feature: https:/elbywan/wretch#fetcherrorcb-error-networkerror-originalrequest-wretcher--any