Don’t fire afterLeave event more than once for a given transition

packages/@headlessui-react/src/components/transitions/transition.test.tsx

@@ -1,4 +1,4 @@
-import React, { Fragment, useState, useRef, useLayoutEffect } from 'react'
+import React, { Fragment, useState, useRef, useLayoutEffect, useEffect } from 'react'
 import { render, fireEvent } from '@testing-library/react'
 
 import { suppressConsoleLogs } from '../../test-utils/suppress-console-logs'
@@ -1397,4 +1397,93 @@ describe('Events', () => {
       ])
     })
   )
+
+  it(
+    'should fire only one event for a given component change',
+    suppressConsoleLogs(async () => {
+      let eventHandler = jest.fn()
+      let enterDuration = 50
+      let leaveDuration = 75
+
+      function Example() {
+        let [show, setShow] = useState(false)
+        let [start, setStart] = useState(Date.now())
+
+        useEffect(() => setStart(Date.now()), [])
+
+        return (
+          <>
+            <style>{`
+              .enter-1 { transition-duration: ${enterDuration * 1}ms; }
+              .enter-2 { transition-duration: ${enterDuration * 2}ms; }
+              .enter-from { opacity: 0%; }
+              .enter-to { opacity: 100%; }
+
+              .leave-1 { transition-duration: ${leaveDuration * 1}ms; }
+              .leave-2 { transition-duration: ${leaveDuration * 2}ms; }
+              .leave-from { opacity: 100%; }
+              .leave-to { opacity: 0%; }
+            `}</style>
+            <Transition.Root
+              show={show}
+              as="div"
+              beforeEnter={() => eventHandler('beforeEnter', Date.now() - start)}
+              afterEnter={() => eventHandler('afterEnter', Date.now() - start)}
+              beforeLeave={() => eventHandler('beforeLeave', Date.now() - start)}
+              afterLeave={() => eventHandler('afterLeave', Date.now() - start)}
+              enter="enter-2"
+              enterFrom="enter-from"
+              enterTo="enter-to"
+              leave="leave-2"
+              leaveFrom="leave-from"
+              leaveTo="leave-to"
+            >
+              <Transition.Child
+                enter="enter-1"
+                enterFrom="enter-from"
+                enterTo="enter-to"
+                leave="leave-1"
+                leaveFrom="leave-from"
+                leaveTo="leave-to"
+              />
+              <Transition.Child
+                enter="enter-1"
+                enterFrom="enter-from"
+                enterTo="enter-to"
+                leave="leave-1"
+                leaveFrom="leave-from"
+                leaveTo="leave-to"
+              >
+                <button data-testid="hide" onClick={() => setShow(false)}>
+                  Hide
+                </button>
+              </Transition.Child>
+            </Transition.Root>
+            <button data-testid="show" onClick={() => setShow(true)}>
+              Show
+            </button>
+          </>
+        )
+      }
+
+      render(<Example />)
+
+      fireEvent.click(document.querySelector('[data-testid=show]')!)
+
+      await new Promise((resolve) => setTimeout(resolve, 1000))
+
+      fireEvent.click(document.querySelector('[data-testid=hide]')!)
+
+      await new Promise((resolve) => setTimeout(resolve, 1000))
+
+      expect(eventHandler).toHaveBeenCalledTimes(4)
+      expect(eventHandler.mock.calls.map(([name]) => name)).toEqual([
+        // Order is important here
+        'beforeEnter',
+        'afterEnter',
+        'beforeLeave',
+        'afterLeave',
+      ])
+    })
+  )
 })

packages/@headlessui-vue/CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- Nothing yet!
+### Fixed
+
+- Don’t fire `afterLeave` event more than once for a given transition ([#2267](https://github.com/tailwindlabs/headlessui/pull/2267))
 
 ## [1.7.9] - 2023-02-03
 

packages/@headlessui-vue/src/components/transitions/transition.test.ts

@@ -1258,4 +1258,93 @@ describe('Events', () => {
       expect(leaveHookDiff).toBeLessThanOrEqual(leaveDuration * 3)
     })
   )
+
+  it(
+    'should fire only one event for a given component change',
+    suppressConsoleLogs(async () => {
+      let eventHandler = jest.fn()
+      let enterDuration = 50
+      let leaveDuration = 75
+
+      withStyles(`
+        .enter-1 { transition-duration: ${enterDuration * 1}ms; }
+        .enter-2 { transition-duration: ${enterDuration * 2}ms; }
+        .enter-from { opacity: 0%; }
+        .enter-to { opacity: 100%; }
+
+        .leave-1 { transition-duration: ${leaveDuration * 1}ms; }
+        .leave-2 { transition-duration: ${leaveDuration * 2}ms; }
+        .leave-from { opacity: 100%; }
+        .leave-to { opacity: 0%; }
+      `)
+
+      let Example = defineComponent({
+        components: { TransitionRoot, TransitionChild },
+        template: html`
+          <TransitionRoot
+            :show="show"
+            as="div"
+            @beforeEnter="eventHandler('beforeEnter', Date.now() - start)"
+            @afterEnter="eventHandler('afterEnter', Date.now() - start)"
+            @beforeLeave="eventHandler('beforeLeave', Date.now() - start)"
+            @afterLeave="eventHandler('afterLeave', Date.now() - start)"
+            enter="enter-2"
+            enterFrom="enter-from"
+            enterTo="enter-to"
+            leave="leave-2"
+            leaveFrom="leave-from"
+            leaveTo="leave-to"
+          >
+            <TransitionChild
+              enter="enter-1"
+              enterFrom="enter-from"
+              enterTo="enter-to"
+              leave="leave-1"
+              leaveFrom="leave-from"
+              leaveTo="leave-to"
+            />
+            <TransitionChild
+              enter="enter-1"
+              enterFrom="enter-from"
+              enterTo="enter-to"
+              leave="leave-1"
+              leaveFrom="leave-from"
+              leaveTo="leave-to"
+            >
+              <button data-testid="hide" @click="show = false" @click="hide">Hide</button>
+            </TransitionChild>
+          </TransitionRoot>
+
+          <button data-testid="show" @click="show = true">Show</button>
+        `,
+        setup() {
+          let show = ref(false)
+          let start = ref(Date.now())
+
+          onMounted(() => (start.value = Date.now()))
+
+          return { show, start, eventHandler }
+        },
+      })
+
+      renderTemplate(Example)
+
+      fireEvent.click(getByTestId('show'))
+
+      await new Promise((resolve) => setTimeout(resolve, 1000))
+
+      fireEvent.click(getByTestId('hide'))
+
+      await new Promise((resolve) => setTimeout(resolve, 1000))
+
+      expect(eventHandler).toHaveBeenCalledTimes(4)
+      expect(eventHandler.mock.calls.map(([name]) => name)).toEqual([
+        // Order is important here
+        'beforeEnter',
+        'afterEnter',
+        'beforeLeave',
+        'afterLeave',
+      ])
+    })
+  )
 })

packages/@headlessui-vue/src/components/transitions/transition.ts

@@ -188,7 +188,7 @@ export let TransitionChild = defineComponent({
     let nesting = useNesting(() => {
       // When all children have been unmounted we can only hide ourselves if and only if we are not
       // transitioning ourselves. Otherwise we would unmount before the transitions are finished.
-      if (!isTransitioning.value) {
+      if (!isTransitioning.value && state.value !== TreeStates.Hidden) {
         state.value = TreeStates.Hidden
         unregister(id)
         emit('afterLeave')