feat: allow for custom response parser with parseResponse (#16)

Co-authored-by: Pooya Parsa <pyapar@gmail.com>

README.md

@@ -47,6 +47,16 @@ We use [conditional exports](https://nodejs.org/api/packages.html#packages_condi
 const { users } = await $fetch('/api/users')
 ```
 
+You can optionally provde a different parser than destr.
+
+```js
+// Use JSON.parse
+await $fetch('/movie?lang=en', { parseResponse: JSON.parse })
+
+// Return text as is
+await $fetch('/movie?lang=en', { parseResponse: txt => txt })
+```
+
 ## ✔️ JSON Body
 
 `$fetch` automatically stringifies request body (if an object is passed) and adds JSON `Content-Type` headers (for `put`, `patch` and `post` requests).

src/fetch.ts

@@ -15,6 +15,7 @@ export interface FetchOptions extends Omit<RequestInit, 'body'> {
   baseURL?: string
   body?: RequestInit['body'] | Record<string, any>
   params?: SearchParams
+  parseResponse?: (responseText: string) => any
   response?: boolean
 }
 
@@ -44,8 +45,8 @@ export function setHeader (options: FetchOptions, _key: string, value: string) {
 }
 
 export function createFetch ({ fetch }: CreateFetchOptions): $Fetch {
-  const raw: $Fetch['raw'] = async function (request, opts) {
-    if (opts && typeof request === 'string') {
+  const raw: $Fetch['raw'] = async function (request, opts = {}) {
+    if (typeof request === 'string') {
       if (opts.baseURL) {
         request = joinURL(opts.baseURL, request)
       }
@@ -59,7 +60,8 @@ export function createFetch ({ fetch }: CreateFetchOptions): $Fetch {
     }
     const response: FetchResponse<any> = await fetch(request, opts as RequestInit)
     const text = await response.text()
-    response.data = destr(text)
+    const parseFn = opts.parseResponse || destr
+    response.data = parseFn(text)
     if (!response.ok) {
       throw createFetchError(request, response)
     }

test/index.test.ts

@@ -8,7 +8,7 @@ describe('ohmyfetch', () => {
   let listener: Listener
   const getURL = (url: string) => joinURL(listener.url, url)
 
-  it('setup', async () => {
+  beforeAll(async () => {
     const app = createApp()
       .use('/ok', () => 'ok')
       .use('/params', req => (getQuery(req.url || '')))
@@ -25,6 +25,12 @@ describe('ohmyfetch', () => {
     expect(await $fetch(getURL('ok'))).toBe('ok')
   })
 
+  it('custom parseResponse', async () => {
+    const parser = jest.fn().mockReturnValue('asdf')
+    await $fetch(getURL('ok'), { parseResponse: parser })
+    expect(parser).toHaveBeenCalledTimes(1)
+  })
+
   it('baseURL', async () => {
     expect(await $fetch('/x?foo=123', { baseURL: getURL('url') })).toBe('/x?foo=123')
   })