Breaking: drop the default fetcher

README.md

@@ -113,7 +113,7 @@ const { data, error, isValidating, mutate } = useSWR(key, fetcher, options)
 #### Options
 
 - `suspense = false`: enable React Suspense mode [(details)](#suspense-mode)
-- `fetcher = window.fetch`: the default fetcher function
+- `fetcher`: the function to retrieve the remote data source
 - `initialData`: initial data to be returned (note: This is per-hook)
 - `revalidateOnMount`: enable or disable automatic revalidation when component is mounted (by default revalidation occurs on mount when initialData is not set, use this flag to force behavior)
 - `revalidateOnFocus = true`: auto revalidate when window gets focused

src/types.ts

@@ -18,7 +18,7 @@ export interface Configuration<
   shouldRetryOnError: boolean
   suspense?: boolean
   initialData?: Data
-  fetcher: Fn
+  fetcher?: Fn
   cache: Cache
   middlewares?: Middleware[]
 

src/utils/config.ts

@@ -6,7 +6,6 @@ import { slowConnection } from './env'
 import { Configuration, RevalidatorOptions, Revalidator } from '../types'
 import { UNDEFINED } from './helper'
 
-const fetcher = (url: string) => fetch(url).then(res => res.json())
 const noop = () => {}
 
 // error retry
@@ -56,7 +55,6 @@ const defaultConfig: Configuration = {
   loadingTimeout: slowConnection ? 5000 : 3000,
 
   // providers
-  fetcher,
   compare: dequal,
   isPaused: () => false,
   cache: wrapCache(new Map()),

test/use-swr-integration.test.tsx

@@ -357,27 +357,4 @@ describe('useSWR', () => {
     expect(fetcher).toBeCalled()
     await screen.findByText('hello, SWR')
   })
-
-  it('should use fetch api as default fetcher', async () => {
-    const users = [{ name: 'bob' }, { name: 'sue' }]
-    global['fetch'] = () => Promise.resolve()
-    const mockFetch = body =>
-      Promise.resolve({ json: () => Promise.resolve(body) } as any)
-    const fn = jest
-      .spyOn(window, 'fetch')
-      .mockImplementation(() => mockFetch(users))
-
-    function Users() {
-      const { data } = useSWR('http://localhost:3000/api/users')
-
-      return <div>hello, {data && data.map(u => u.name).join(' and ')}</div>
-    }
-
-    render(<Users />)
-    screen.getByText('hello,')
-    expect(fn).toBeCalled()
-
-    await screen.findByText('hello, bob and sue')
-    delete global['fetch']
-  })
 })