Ensure Transition component completes if nothing is transitioning (#2318)

* make `disposables` consistent

Also added a `group` function, this allows us to spawn a _sub_
disposables group that can be disposed on its own, but will also be
disposed the moment the "parent" is disposed.

* ensure Transition component works when nothing is transitioning

* update changelog

packages/@headlessui-react/CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- Nothing yet!
+### Fixed
+
+- Ensure `Transition` component completes if nothing is transitioning ([#2318](https://github.com/tailwindlabs/headlessui/pull/2318))
 
 ## [1.7.12] - 2023-02-24
 

packages/@headlessui-react/src/components/transitions/utils/transition.ts

@@ -39,6 +39,23 @@ function waitForTransition(node: HTMLElement, done: () => void) {
         dispose()
       }, totalDuration)
     } else {
+      d.group((d) => {
+        // Mark the transition as done when the timeout is reached. This is a fallback in case the
+        // transitionrun event is not fired.
+        d.setTimeout(() => {
+          done()
+          d.dispose()
+        }, totalDuration)
+
+        // The moment the transitionrun event fires, we should cleanup the timeout fallback, because
+        // then we know that we can use the native transition events because something is
+        // transitioning.
+        d.addEventListener(node, 'transitionrun', (event) => {
+          if (event.target !== event.currentTarget) return
+          d.dispose()
+        })
+      })
+
       let dispose = d.addEventListener(node, 'transitionend', (event) => {
         if (event.target !== event.currentTarget) return
         done()

packages/@headlessui-react/src/utils/disposables.ts

@@ -3,7 +3,7 @@ import { microTask } from './micro-task'
 export type Disposables = ReturnType<typeof disposables>
 
 export function disposables() {
-  let disposables: Function[] = []
+  let _disposables: Function[] = []
 
   let api = {
     addEventListener<TEventName extends keyof WindowEventMap>(
@@ -44,23 +44,6 @@ export function disposables() {
       })
     },
 
-    add(cb: () => void) {
-      disposables.push(cb)
-      return () => {
-        let idx = disposables.indexOf(cb)
-        if (idx >= 0) {
-          let [dispose] = disposables.splice(idx, 1)
-          dispose()
-        }
-      }
-    },
-
-    dispose() {
-      for (let dispose of disposables.splice(0)) {
-        dispose()
-      }
-    },
-
     style(node: HTMLElement, property: string, value: string) {
       let previous = node.style.getPropertyValue(property)
       Object.assign(node.style, { [property]: value })
@@ -68,6 +51,30 @@ export function disposables() {
         Object.assign(node.style, { [property]: previous })
       })
     },
+
+    group(cb: (d: typeof this) => void) {
+      let d = disposables()
+      cb(d)
+      return this.add(() => d.dispose())
+    },
+
+    add(cb: () => void) {
+      _disposables.push(cb)
+      return () => {
+        let idx = _disposables.indexOf(cb)
+        if (idx >= 0) {
+          for (let dispose of _disposables.splice(idx, 1)) {
+            dispose()
+          }
+        }
+      }
+    },
+
+    dispose() {
+      for (let dispose of _disposables.splice(0)) {
+        dispose()
+      }
+    },
   }
 
   return api

packages/@headlessui-vue/src/utils/disposables.ts

@@ -1,7 +1,7 @@
 export type Disposables = ReturnType<typeof disposables>
 
 export function disposables() {
-  let disposables: Function[] = []
+  let _disposables: Function[] = []
 
   let api = {
     addEventListener<TEventName extends keyof WindowEventMap>(
@@ -30,10 +30,6 @@ export function disposables() {
       api.add(() => clearTimeout(timer))
     },
 
-    add(cb: () => void) {
-      disposables.push(cb)
-    },
-
     style(node: HTMLElement, property: string, value: string) {
       let previous = node.style.getPropertyValue(property)
       Object.assign(node.style, { [property]: value })
@@ -42,8 +38,26 @@ export function disposables() {
       })
     },
 
+    group(cb: (d: typeof this) => void) {
+      let d = disposables()
+      cb(d)
+      return this.add(() => d.dispose())
+    },
+
+    add(cb: () => void) {
+      _disposables.push(cb)
+      return () => {
+        let idx = _disposables.indexOf(cb)
+        if (idx >= 0) {
+          for (let dispose of _disposables.splice(idx, 1)) {
+            dispose()
+          }
+        }
+      }
+    },
+
     dispose() {
-      for (let dispose of disposables.splice(0)) {
+      for (let dispose of _disposables.splice(0)) {
         dispose()
       }
     },