yarn add @pacote/ffetch

In its simplest form, ffetch works a lot like the Fetch API it wraps:

import { ffetch } from '@pacote/ffetch'

const response = await ffetch('https://goblindegook.com/api/kittens/1').run()

console.log(result.value) // yields either an error or the response body

The function conveniently abstracts away concerns like response body parsing and some error handling.

However, the main difference and biggest selling point is that ffetch creates a TaskEither object which doesn't immediately run and allows chaining extra functionality. For example, you could more simply implement features like request cancellation and retrying around such an abstraction.

In the example above, executing ffetch(...).run() returns a Promise like the Fetch API does. But instead of resolving to a successful response (or rejecting on error), this Promise resolves to an Either representation that holds the successfully obtained and parsed response (on the right) or any of the possible errors that can arise (on the left).

Whatever the result, it can be directly accessed via the value property, but Either also allows handling responses safely through mapping functions, all without resorting to (sometimes nested) try ... catch constructs. For example:

import { ffetch } from '@pacote/ffetch'

// Perform the request:
const response = await ffetch('https://goblindegook.com/api/kittens/1').run()

// Handling success and failure responses separately:
response
  .map(body => {
    /* handle successful response */
    return body
  })
  .leftMap(error => {
    /* handle request failure */
    return error
  })
)

// Get the successful response body falling back to some default value:
const okOrDefault = response.getOrElse('some default value')

MIT © Luís Rodrigues.