Lazily resolve default containers in <Dialog> (#2697)

* Lazily resolve default containers in `<Dialog>`

* Update changelog

packages/@headlessui-react/CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Don't call `<Dialog>`'s `onClose` twice on mobile devices ([#2690](https://github.com/tailwindlabs/headlessui/pull/2690))
+- Lazily resolve default containers in `<Dialog>` ([#2697](https://github.com/tailwindlabs/headlessui/pull/2697))
 
 ## [1.7.17] - 2023-08-17
 

packages/@headlessui-react/src/components/dialog/dialog.test.tsx

@@ -1525,6 +1525,43 @@ describe('Mouse interactions', () => {
     })
   )
 
+  // NOTE: This test doesn't actually fail in JSDOM when it's supposed to
+  // We're keeping it around for documentation purposes
+  it(
+    'should not close the Dialog if it starts open and we click inside the Dialog when it has only a panel',
+    suppressConsoleLogs(async () => {
+      function Example() {
+        let [isOpen, setIsOpen] = useState(true)
+        return (
+          <>
+            <button id="trigger" onClick={() => setIsOpen((v) => !v)}>
+              Trigger
+            </button>
+            <Dialog open={isOpen} onClose={() => setIsOpen(false)}>
+              <Dialog.Panel>
+                <p id="inside">My content</p>
+                <button>close</button>
+              </Dialog.Panel>
+            </Dialog>
+          </>
+        )
+      }
+
+      render(<Example />)
+
+      // Open the dialog
+      await click(document.getElementById('trigger'))
+
+      assertDialog({ state: DialogState.Visible })
+
+      // Click the p tag inside the dialog
+      await click(document.getElementById('inside'))
+
+      // It should not have closed
+      assertDialog({ state: DialogState.Visible })
+    })
+  )
+
   it(
     'should close the Dialog if we click outside the Dialog.Panel',
     suppressConsoleLogs(async () => {

packages/@headlessui-react/src/components/dialog/dialog.tsx

@@ -14,6 +14,7 @@ import React, {
   ContextType,
   ElementType,
   MouseEvent as ReactMouseEvent,
+  RefObject,
   MutableRefObject,
   Ref,
 } from 'react'
@@ -210,13 +211,24 @@ function DialogFn<TTag extends ElementType = typeof DEFAULT_DIALOG_TAG>(
   let hasNestedDialogs = nestedDialogCount > 1 // 1 is the current dialog
   let hasParentDialog = useContext(DialogContext) !== null
   let [portals, PortalWrapper] = useNestedPortals()
+
+  // We use this because reading these values during iniital render(s)
+  // can result in `null` rather then the actual elements
+  // This doesn't happen when using certain components like a
+  // `<Dialog.Title>` because they cause the parent to re-render
+  let defaultContainer: RefObject<HTMLElement> = {
+    get current() {
+      return state.panelRef.current ?? internalDialogRef.current
+    },
+  }
+
   let {
     resolveContainers: resolveRootContainers,
     mainTreeNodeRef,
     MainTreeNode,
   } = useRootContainers({
     portals,
-    defaultContainers: [state.panelRef.current ?? internalDialogRef.current],
+    defaultContainers: [defaultContainer],
   })
 
   // If there are multiple dialogs, then you can be the root, the leaf or one