fetchmap

fetchmap

Non-throwing fetch wrapper

Getting started

npm i fetchmap

Description

This is a simple wrapper for standard fetch function that catches all possible exceptions and returns a 'success or failure' wrapped value. It takes an object to map response.status to (response: Response) => unknown transform, standard fetch arguments and a fetch function itself. The last argument can be curried.

Example

// server code
import express from 'express'

express()
  .get('/json', (_, res) => {
    res.json({ some: 'data' })
  })
  .listen(5005)

// client code
import { fetchmap } from 'fetchmap'

const json_success = await fetchmap({ ok: 'json' }, 'https://localhost:5005/json')(fetch)
expect(json_success).toEqual({ tag: 'success', success: { some: 'data' } })

const json_success_only_200 = await fetchmap({ 200: 'json' }, 'https://localhost:5005/json')(fetch)
expect(json_success_only_200).toEqual({ tag: 'success', success: { some: 'data' } })

const invalid_url_failure_non_curried_form = await fetchmap({}, '1234', undefined, fetch)
expect(invalid_url_failure_non_curried_form).toEqual({
  tag: 'failure',
  failure: { clientError: new TypeError('Only absolute URLs are supported') }
})

const not_found_error_with_request_init = await fetchmap(
  { notOk: ({ status }: Response) => status },
  'https://localhost:5005/invalid',
  { method: 'POST', credentials: 'include' }
)(fetch)
expect(not_found_error_with_request_init).toEqual({ tag: 'failure', failure: { serverError: 404 } })

Usage

See test or playground

Misc

ts-railway - compatible result library