fix(debounceFilter): invoke on maxWait with the latest invoker (#4497)

Co-authored-by: Robin Kehl <[email protected]>
Co-authored-by: OrbisK <[email protected]>

packages/shared/utils/filters.ts

@@ -73,6 +73,8 @@ export function debounceFilter(ms: MaybeRefOrGetter<number>, options: DebounceFi
     lastRejector = noop
   }
 
+  let lastInvoker: () => void
+
   const filter: EventFilter = (invoke) => {
     const duration = toValue(ms)
     const maxDuration = toValue(options.maxWait)
@@ -90,13 +92,14 @@ export function debounceFilter(ms: MaybeRefOrGetter<number>, options: DebounceFi
 
     return new Promise((resolve, reject) => {
       lastRejector = options.rejectOnCancel ? reject : resolve
+      lastInvoker = invoke
       // Create the maxTimer. Clears the regular timer on invoke
       if (maxDuration && !maxTimer) {
         maxTimer = setTimeout(() => {
           if (timer)
             _clearTimeout(timer)
           maxTimer = null
-          resolve(invoke())
+          resolve(lastInvoker())
         }, maxDuration)
       }
 

packages/shared/watchDebounced/index.test.ts

@@ -42,6 +42,33 @@ describe('watchDebounced', () => {
     num.value = 5
     await vi.advanceTimersByTimeAsync(75)
     expect(cb).toHaveBeenCalledTimes(2)
-    expect(cb).toHaveBeenCalledWith(4, 2, expect.anything())
+    expect(cb).toHaveBeenCalledWith(5, 4, expect.anything())
+  })
+
+  it('should work with constant changes over multiple maxWaits', async () => {
+    vi.useFakeTimers()
+    const num = ref(0)
+    const cb = vi.fn()
+
+    const constantUpdateOverTime = async (ms: number) => {
+      for (let i = 0; i < ms; i++) {
+        num.value += 1
+        await vi.advanceTimersByTimeAsync(1)
+      }
+    }
+    watchDebounced(num, cb, { debounce: 10, maxWait: 50 })
+    expect(cb).toHaveBeenCalledTimes(0)
+    await constantUpdateOverTime(49)
+    expect(cb).toHaveBeenCalledTimes(0)
+    await constantUpdateOverTime(1)
+    expect(cb).toHaveBeenCalledTimes(1)
+    await constantUpdateOverTime(50)
+    expect(cb).toHaveBeenCalledTimes(2)
+    await constantUpdateOverTime(50)
+
+    expect(cb).toHaveBeenCalledTimes(3)
+    expect(cb.mock.calls[0][0]).toBe(50)
+    expect(cb.mock.calls[1][0]).toBe(100)
+    expect(cb.mock.calls[2][0]).toBe(150)
   })
 })