From 9d3b0ff611b25191e94b3e67c1c04fd16567cd70 Mon Sep 17 00:00:00 2001
From: Robin Malfait <malfait.robin@gmail.com>
Date: Fri, 4 Apr 2025 14:16:42 +0200
Subject: [PATCH] Fix `Unexpected undefined` crash in `Combobox` component with
 `virtual` mode (#3678)

This PR fixes an issue where the `Combobox` component crashes if you are
using the `virtual` option and you quickly type something such that the
`Combobox` opens but no valid options are available.

We already check if the current active index is available in the
internal `options` list. However, if you then call
`virtualizer.scrollToIndex(data.activeOptionIndex)` it will crash if you
are too fast.


https://github.com/user-attachments/assets/f48172e6-4098-4a31-aa16-67ce21f074d1

If you are typing slowly, then it will work as expected.


https://github.com/user-attachments/assets/9d522bd5-5b54-4c12-9250-a2d92a511b35

I did find an open issue on TanStack's repo about this:
https://github.com/TanStack/virtual/issues/879

This PR is basically a workaround by delaying the call. But it does have
the expected behavior now.


https://github.com/user-attachments/assets/2e5e47a5-b021-4897-b098-568711723b77


Fixes: #3583
---
 packages/@headlessui-react/CHANGELOG.md              |  1 +
 .../src/components/combobox/combobox.tsx             | 12 +++++++++---
 .../react/pages/combobox/combobox-virtualized.tsx    |  4 ++--
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/packages/@headlessui-react/CHANGELOG.md b/packages/@headlessui-react/CHANGELOG.md
index 55e8fc2..3d0cc86 100644
--- a/packages/@headlessui-react/CHANGELOG.md
+++ b/packages/@headlessui-react/CHANGELOG.md
@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Bump `@tanstack/react-virtual` to fix warnings in React 19 projects ([#3588](https://github.com/tailwindlabs/headlessui/pull/3588))
 - Fix `aria-invalid` attributes to have a valid `'true'` value ([#3639](https://github.com/tailwindlabs/headlessui/pull/3639))
 - Add missing `invalid` prop to `Combobox` component ([#3677](https://github.com/tailwindlabs/headlessui/pull/3677))
+- Fix `Unexpected undefined` crash in `Combobox` component with `virtual` mode ([#3678](https://github.com/tailwindlabs/headlessui/pull/3678))
 
 ## [2.2.0] - 2024-10-25
 
diff --git a/packages/@headlessui-react/src/components/combobox/combobox.tsx b/packages/@headlessui-react/src/components/combobox/combobox.tsx
index d0dce90..fd364bc 100644
--- a/packages/@headlessui-react/src/components/combobox/combobox.tsx
+++ b/packages/@headlessui-react/src/components/combobox/combobox.tsx
@@ -479,6 +479,7 @@ function VirtualProvider(props: {
   children: (data: { option: unknown; open: boolean }) => React.ReactElement
 }) {
   let data = useData('VirtualProvider')
+  let d = useDisposables()
   let { options } = data.virtual!
 
   let [paddingStart, paddingEnd] = useMemo(() => {
@@ -528,6 +529,7 @@ function VirtualProvider(props: {
         }}
         ref={(el) => {
           if (!el) {
+            d.dispose()
             return
           }
 
@@ -537,9 +539,13 @@ function VirtualProvider(props: {
           }
 
           // Scroll to the active index
-          if (data.activeOptionIndex !== null && options.length > data.activeOptionIndex) {
-            virtualizer.scrollToIndex(data.activeOptionIndex)
-          }
+          //
+          // Workaround for: https://github.com/TanStack/virtual/issues/879
+          d.nextFrame(() => {
+            if (data.activeOptionIndex !== null && options.length > data.activeOptionIndex) {
+              virtualizer.scrollToIndex(data.activeOptionIndex)
+            }
+          })
         }}
       >
         {items.map((item) => {
diff --git a/playgrounds/react/pages/combobox/combobox-virtualized.tsx b/playgrounds/react/pages/combobox/combobox-virtualized.tsx
index 9873ff5..e8307ac 100644
--- a/playgrounds/react/pages/combobox/combobox-virtualized.tsx
+++ b/playgrounds/react/pages/combobox/combobox-virtualized.tsx
@@ -108,7 +108,7 @@ function Example({ virtual = true, data, initial }: { virtual?: boolean; data; i
                 <Combobox.Options
                   transition
                   anchor="bottom start"
-                  className="w-[calc(var(--input-width)+var(--button-width))] overflow-auto rounded-md bg-white py-1 text-base leading-6 shadow-lg transition duration-1000 [--anchor-gap:theme(spacing.1)] [--anchor-max-height:theme(spacing.60)] focus:outline-none data-[closed]:opacity-0 sm:text-sm sm:leading-5"
+                  className="w-[calc(var(--input-width)+var(--button-width))] overflow-auto rounded-md bg-white py-1 text-base leading-6 shadow-lg transition duration-300 [--anchor-gap:theme(spacing.1)] [--anchor-max-height:theme(spacing.60)] focus:outline-none data-[closed]:opacity-0 sm:text-sm sm:leading-5"
                 >
                   {({ option }) => {
                     return (
@@ -157,7 +157,7 @@ function Example({ virtual = true, data, initial }: { virtual?: boolean; data; i
                 <Combobox.Options
                   transition
                   anchor="bottom start"
-                  className="w-[calc(var(--input-width)+var(--button-width))] overflow-auto rounded-md bg-white py-1 text-base leading-6 shadow-lg transition duration-1000 [--anchor-gap:theme(spacing.1)] [--anchor-max-height:theme(spacing.60)] focus:outline-none data-[closed]:opacity-0 sm:text-sm sm:leading-5"
+                  className="w-[calc(var(--input-width)+var(--button-width))] overflow-auto rounded-md bg-white py-1 text-base leading-6 shadow-lg transition duration-300 [--anchor-gap:theme(spacing.1)] [--anchor-max-height:theme(spacing.60)] focus:outline-none data-[closed]:opacity-0 sm:text-sm sm:leading-5"
                 >
                   {timezones.map((timezone, idx) => {
                     return (