fetch wrapper and error management

[0gust1]

Hi,

• Our sveltekit apps use Typescript
• endpoints are calling "service modules" (DB, server-side HTTP calls to other services, etc.)
• we use the "neverthrow" pattern: in those "service modules", function should never throw but always return an union type typedData | serviceError (it's more an Either type, in fact)
• as seen above, we wrap the errors into custom error classes to have better control over the logging behavior and the messages displayed to the end-user (which can be different).

We want to wrap the fetch behavior to generalize the usage of those custom Error classes.

We use fetch on:

• client-side
• "middle-side" (load function)
• server-side (calls to external HTTP services).

Ideally we would like to have a single "fetchWrapper" lib, able to be typed (probably using generics) and handling errors as close as possible as the principles described above.

Question(s)

1. does it seem a god idea to you? if so, are you interested by some feedbacks ?
2. does it seems the right time to do so ? it seems there is a lot of movement on the RequestHandler / load function typing recently
3. sveltekit on middle-side (load function) and server-side (endpoint) use its own version of fetch (to handle the svelte-kit rendering behavior). It seems we can build upon it, but we're still unsure of the potential side effects of building our own fetchWrapper upon the svletekit's fetch. Do you have some pointers on the sveltekit's fetch particularities/handling ? (e.g. we're still unsure about the fallthrough handling and the backed in svletekit error management)

[0gust1]

We're still working (slowly, as we have a product to ship 😄 ) on the topic.

A good example of what we start to have, on typescript level, is types definitions and "algebraic data types" (Either, Left, Right) that looks like things provided by repos like:

• https://swan-io.github.io/boxed/
• https://gigobyte.github.io/purify/
• https://gcanti.github.io/fp-ts/
• etc.

Do the sveltekit team (working on TS support) is interested/planned this kind of modelisation ?