Add preload cache clear

src/_internal/index.ts

@@ -22,7 +22,7 @@ export { getTimestamp } from './utils/timestamp'
 export { useSWRConfig } from './utils/use-swr-config'
 export { preset, defaultConfigOptions } from './utils/web-preset'
 export { withMiddleware } from './utils/with-middleware'
-export { preload } from './utils/preload'
+export { preload, clearPreloadCache } from './utils/preload'
 
 export * from './types'
 

src/_internal/utils/preload.ts

@@ -39,6 +39,13 @@ export const preload = <
   return req
 }
 
+export const clearPreloadCache = () => {
+  const globalState = SWRGlobalState.get(cache) as GlobalState
+
+  // index 3 are PRELOAD
+  globalState[3] = Object.create(null)
+}
+
 export const middleware: Middleware =
   useSWRNext => (key_, fetcher_, config) => {
     // fetcher might be a sync function, so this should not be an async function

src/index/index.ts

@@ -6,7 +6,7 @@ export { SWRConfig } from './use-swr'
 export { unstable_serialize } from './serialize'
 export { useSWRConfig } from '../_internal'
 export { mutate } from '../_internal'
-export { preload } from '../_internal'
+export { preload, clearPreloadCache } from '../_internal'
 
 // Config
 

test/use-swr-preload.test.tsx

@@ -1,6 +1,6 @@
 import { act, fireEvent, screen } from '@testing-library/react'
 import { Suspense, useEffect, useState, Profiler } from 'react'
-import useSWR, { preload, useSWRConfig } from 'swr'
+import useSWR, { preload, clearPreloadCache, useSWRConfig } from 'swr'
 import {
   createKey,
   createResponse,
@@ -224,4 +224,24 @@ describe('useSWR - preload', () => {
     preload(() => key, fetcher)
     expect(calledWith).toBe(key)
   })
+
+  it('re-call fetcher when preload cache are cleared', async () => {
+    const key = createKey()
+
+    const fetcher = jest.fn(() => createResponse('foo'))
+
+    function Page() {
+      const { data } = useSWR(key, fetcher)
+      return <div>data:{data}</div>
+    }
+
+    preload(key, fetcher)
+    expect(fetcher).toBeCalledTimes(1)
+
+    clearPreloadCache()
+
+    renderWithGlobalCache(<Page />)
+    await screen.findByText('data:foo')
+    expect(fetcher).toBeCalledTimes(2)
+  })
 })