fix(useDebouncedCallback): fix behavior in strict mode (#98)

Author: kyletsang

src/useDebouncedCallback.ts

@@ -1,7 +1,7 @@
-import { useCallback, useMemo, useRef } from 'react'
+import { useMemo, useRef } from 'react'
 import useTimeout from './useTimeout'
-import useMounted from './useMounted'
 import useEventCallback from './useEventCallback'
+import useWillUnmount from './useWillUnmount'
 
 export interface UseDebouncedCallbackOptions {
   wait: number
@@ -55,6 +55,8 @@ function useDebouncedCallback<TCallback extends (...args: any[]) => any>(
 
   const isTimerSetRef = useRef(false)
   const lastArgsRef = useRef<unknown[] | null>(null)
+  // Use any to bypass type issue with setTimeout.
+  const timerRef = useRef<any>(0)
 
   const handleCallback = useEventCallback(fn)
 
@@ -69,6 +71,11 @@ function useDebouncedCallback<TCallback extends (...args: any[]) => any>(
 
   const timeout = useTimeout()
 
+  useWillUnmount(() => {
+    clearTimeout(timerRef.current)
+    isTimerSetRef.current = false
+  })
+
   return useMemo(() => {
     const hasMaxWait = !!maxWait
 
@@ -161,14 +168,14 @@ function useDebouncedCallback<TCallback extends (...args: any[]) => any>(
         if (hasMaxWait) {
           // Handle invocations in a tight loop.
           isTimerSetRef.current = true
-          setTimeout(timerExpired, wait)
+          timerRef.current = setTimeout(timerExpired, wait)
           return invokeFunc(lastCallTimeRef.current)
         }
       }
 
       if (!isTimerSetRef.current) {
         isTimerSetRef.current = true
-        setTimeout(timerExpired, wait)
+        timerRef.current = setTimeout(timerExpired, wait)
       }
 
       return returnValueRef.current