feat: accept a className in mountNode in Portal

change/@fluentui-react-portal-d5ac98ba-22cc-41a1-939d-77041a362442.json

@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: accept a className in mountNode in Portal",
+  "packageName": "@fluentui/react-portal",
+  "email": "[email protected]",
+  "dependentChangeType": "patch"
+}

packages/react-components/react-portal/etc/react-portal.api.md

@@ -15,11 +15,15 @@ export const Portal: React_2.FC<PortalProps>;
 // @public (undocumented)
 export type PortalProps = {
     children?: React_2.ReactNode;
-    mountNode?: HTMLElement | null;
+    mountNode?: HTMLElement | null | {
+        element?: HTMLElement | null;
+        className?: string;
+    };
 };
 
 // @public (undocumented)
-export type PortalState = Pick<PortalProps, 'children'> & Required<Pick<PortalProps, 'mountNode'>> & {
+export type PortalState = Pick<PortalProps, 'children'> & {
+    mountNode: HTMLElement | null | undefined;
     virtualParentRootRef: React_2.MutableRefObject<HTMLSpanElement | null>;
 };
 

packages/react-components/react-portal/src/components/Portal/Portal.types.ts

@@ -11,13 +11,14 @@ export type PortalProps = {
    *
    * @default a new element on document.body without any styling
    */
-  mountNode?: HTMLElement | null;
+  mountNode?: HTMLElement | null | { element?: HTMLElement | null; className?: string };
 };
 
-export type PortalState = Pick<PortalProps, 'children'> &
-  Required<Pick<PortalProps, 'mountNode'>> & {
-    /**
-     * Ref to the root span element as virtual parent
-     */
-    virtualParentRootRef: React.MutableRefObject<HTMLSpanElement | null>;
-  };
+export type PortalState = Pick<PortalProps, 'children'> & {
+  mountNode: HTMLElement | null | undefined;
+
+  /**
+   * Ref to the root span element as virtual parent
+   */
+  virtualParentRootRef: React.MutableRefObject<HTMLSpanElement | null>;
+};

packages/react-components/react-portal/src/components/Portal/usePortal.test.ts

@@ -0,0 +1,33 @@
+import { toMountNodeProps } from './usePortal';
+
+describe('toMountNodeProps', () => {
+  it('handles HTMLElement', () => {
+    const element = document.createElement('div');
+
+    expect(toMountNodeProps(element)).toMatchObject({
+      element,
+    });
+  });
+
+  it('handles "null"', () => {
+    expect(toMountNodeProps(null)).toMatchObject({
+      element: null,
+    });
+  });
+
+  it('handles "undefined"', () => {
+    expect(toMountNodeProps(null)).toMatchObject({});
+  });
+
+  it('handles objects', () => {
+    const element = document.createElement('div');
+
+    expect(toMountNodeProps({ element })).toMatchObject({
+      element,
+    });
+    expect(toMountNodeProps({ element, className: 'foo' })).toMatchObject({
+      element,
+      className: 'foo',
+    });
+  });
+});

packages/react-components/react-portal/src/components/Portal/usePortal.ts

@@ -1,8 +1,29 @@
+import { isHTMLElement } from '@fluentui/react-utilities';
 import * as React from 'react';
-import { usePortalMountNode } from './usePortalMountNode';
+
 import { setVirtualParent } from '../../virtualParent/index';
+import { usePortalMountNode } from './usePortalMountNode';
 import type { PortalProps, PortalState } from './Portal.types';
 
+export function toMountNodeProps(mountNode: PortalProps['mountNode']): {
+  element?: HTMLElement | null;
+  className?: string;
+} {
+  if (isHTMLElement(mountNode)) {
+    return { element: mountNode };
+  }
+
+  if (typeof mountNode === 'object') {
+    if (mountNode === null) {
+      return { element: null };
+    }
+
+    return mountNode;
+  }
+
+  return {};
+}
+
 /**
  * Create the state required to render Portal.
  *
@@ -11,14 +32,14 @@ import type { PortalProps, PortalState } from './Portal.types';
  * @param props - props from this instance of Portal
  */
 export const usePortal_unstable = (props: PortalProps): PortalState => {
-  const { children, mountNode } = props;
+  const { element, className } = toMountNodeProps(props.mountNode);
 
   const virtualParentRootRef = React.useRef<HTMLSpanElement>(null);
-  const fallbackMountNode = usePortalMountNode({ disabled: !!mountNode });
+  const fallbackElement = usePortalMountNode({ disabled: !!element, className });
 
   const state: PortalState = {
-    children,
-    mountNode: mountNode ?? fallbackMountNode,
+    children: props.children,
+    mountNode: element ?? fallbackElement,
     virtualParentRootRef,
   };
 

packages/react-components/react-portal/src/components/Portal/usePortalMountNode.test.ts

@@ -0,0 +1,23 @@
+import { renderHook } from '@testing-library/react-hooks';
+import { usePortalMountNode } from './usePortalMountNode';
+
+describe('usePortalMountNode', () => {
+  it('creates an element and attaches it to "document.body"', () => {
+    const { result } = renderHook(() => usePortalMountNode({}));
+
+    expect(result.current).toBeInstanceOf(HTMLDivElement);
+    expect(document.body.contains(result.current)).toBeTruthy();
+  });
+
+  it('applies classes to an element', () => {
+    const { result } = renderHook(() => usePortalMountNode({ className: 'foo' }));
+
+    expect(result.current?.classList).toContain('foo');
+  });
+
+  it('does not create an element if is disabled', () => {
+    const { result } = renderHook(() => usePortalMountNode({ disabled: true }));
+
+    expect(result.current).toBeNull();
+  });
+});

packages/react-components/react-portal/src/components/Portal/usePortalMountNode.ts

@@ -7,13 +7,15 @@ import { makeStyles, mergeClasses } from '@griffel/react';
 import { useFocusVisible } from '@fluentui/react-tabster';
 import { useDisposable } from 'use-disposable';
 
-const useInsertionEffect = (React as never)['useInsertion' + 'Effect'] as typeof React.useLayoutEffect;
+const useInsertionEffect = (React as never)['useInsertion' + 'Effect'] as typeof React.useLayoutEffect | undefined;
 
 export type UsePortalMountNodeOptions = {
   /**
    * Since hooks cannot be called conditionally use this flag to disable creating the node
    */
   disabled?: boolean;
+
+  className?: string;
 };
 
 const useStyles = makeStyles({
@@ -23,18 +25,16 @@ const useStyles = makeStyles({
   },
 });
 
-const reactMajorVersion = Number(React.version.split('.')[0]);
-
 /**
- * Creates a new element on a document.body to mount portals
+ * Creates a new element on a "document.body" to mount portals.
  */
 export const usePortalMountNode = (options: UsePortalMountNodeOptions): HTMLElement | null => {
   const { targetDocument, dir } = useFluent();
   const focusVisibleRef = useFocusVisible<HTMLDivElement>() as React.MutableRefObject<HTMLElement | null>;
   const classes = useStyles();
   const themeClassName = useThemeClassName();
 
-  const className = mergeClasses(themeClassName, classes.root);
+  const className = mergeClasses(themeClassName, classes.root, options.className);
 
   const element = useDisposable(() => {
     if (targetDocument === undefined || options.disabled) {
@@ -46,7 +46,7 @@ export const usePortalMountNode = (options: UsePortalMountNodeOptions): HTMLElem
     return [newElement, () => newElement.remove()];
   }, [targetDocument]);
 
-  if (reactMajorVersion >= 18) {
+  if (useInsertionEffect) {
     // eslint-disable-next-line react-hooks/rules-of-hooks
     useInsertionEffect(() => {
       if (!element) {