fix(ContextualMenu): Context menu focuses first item on opening

src/components/ContextualMenu/ContextualMenu.test.tsx

@@ -1,10 +1,10 @@
 import { render, screen, within } from "@testing-library/react";
 import React from "react";
 
-import ContextualMenu, { Label } from "./ContextualMenu";
-import { Label as DropdownLabel } from "./ContextualMenuDropdown/ContextualMenuDropdown";
 import userEvent from "@testing-library/user-event";
 import Button from "../Button";
+import ContextualMenu, { Label } from "./ContextualMenu";
+import { Label as DropdownLabel } from "./ContextualMenuDropdown/ContextualMenuDropdown";
 
 describe("ContextualMenu ", () => {
   afterEach(() => {
@@ -301,4 +301,94 @@ describe("ContextualMenu ", () => {
     await userEvent.click(screen.getByTestId("child-span"));
     expect(screen.getByLabelText(DropdownLabel.Dropdown)).toBeInTheDocument();
   });
+
+  describe("focus behavior", () => {
+    const setup = (props = {}) => {
+      const links = [0, 1, 2].map((i) => ({
+        "data-testid": `item-${i}`,
+        children: `Item ${i}`,
+      }));
+      const user = userEvent.setup({ advanceTimers: jest.advanceTimersByTime });
+      const utils = render(
+        <ContextualMenu
+          links={links}
+          dropdownProps={{ "data-testid": "dropdown" }}
+          position="right"
+          toggleLabel={<span>toggle</span>}
+          {...props}
+        />,
+      );
+      const toggle = screen.getByRole("button", { name: /toggle/i });
+      return { ...utils, user, toggle, links };
+    };
+
+    beforeEach(() => {
+      jest.useFakeTimers();
+    });
+
+    it("focuses the first item when menu opens", async () => {
+      const { user, toggle } = setup();
+
+      await user.tab();
+      expect(toggle).toHaveFocus();
+      await user.keyboard("{Enter}");
+
+      jest.runOnlyPendingTimers();
+      expect(screen.getByTestId("item-0")).toHaveFocus();
+    });
+
+    it("traps focus", async () => {
+      const { user, links } = setup();
+
+      await user.tab();
+      await user.keyboard("{Enter}");
+      jest.runOnlyPendingTimers();
+
+      const firstItem = screen.getByTestId("item-0");
+      const lastItem = screen.getByTestId(`item-${links.length - 1}`);
+
+      // Tab to the end
+      for (let i = 0; i < links.length - 1; i++) {
+        await user.keyboard("{Tab}");
+      }
+      expect(lastItem).toHaveFocus();
+
+      // Wrap to start
+      await user.keyboard("{Tab}");
+      expect(firstItem).toHaveFocus();
+
+      // Wrap backwards
+      await user.keyboard("{Shift>}{Tab}{/Shift}");
+      expect(lastItem).toHaveFocus();
+    });
+
+    it("does not autofocus when opened by a mouse", async () => {
+      const { user, toggle } = setup();
+
+      await user.click(toggle);
+      jest.runOnlyPendingTimers();
+
+      expect(screen.getByTestId("item-0")).not.toHaveFocus();
+    });
+
+    it("cleans up focus event listeners when unmounted", async () => {
+      const { user, toggle, unmount } = setup();
+
+      await user.click(toggle);
+      unmount();
+      jest.runOnlyPendingTimers();
+
+      expect(document.activeElement).not.toBe(toggle);
+    });
+
+    it("does not autofocus when focusFirstItemOnOpen is false", async () => {
+      const { user, toggle } = setup({ focusFirstItemOnOpen: false });
+
+      await user.tab();
+      await user.keyboard("{Enter}");
+
+      jest.runOnlyPendingTimers();
+      expect(toggle).toHaveFocus();
+    });
+  });
 });

src/components/ContextualMenu/ContextualMenu.tsx

@@ -1,19 +1,25 @@
 import classNames from "classnames";
-import React, { useCallback, useEffect, useId, useRef, useState } from "react";
-import type { HTMLProps, ReactNode } from "react";
+import { usePortal } from "external";
 import { useListener, usePrevious } from "hooks";
-import Button from "../Button";
-import type { ButtonProps } from "../Button";
-import ContextualMenuDropdown from "./ContextualMenuDropdown";
-import type { ContextualMenuDropdownProps } from "./ContextualMenuDropdown";
-import type { MenuLink, Position } from "./ContextualMenuDropdown";
+import type { HTMLProps, ReactNode } from "react";
+import React, { useCallback, useEffect, useId, useRef, useState } from "react";
 import {
   ClassName,
   ExclusiveProps,
   PropsWithSpread,
   SubComponentProps,
 } from "types";
-import { usePortal } from "external";
+import type { ButtonProps } from "../Button";
+import Button from "../Button";
+import type {
+  ContextualMenuDropdownProps,
+  MenuLink,
+  Position,
+} from "./ContextualMenuDropdown";
+import ContextualMenuDropdown from "./ContextualMenuDropdown";
+
+const focusableElementSelectors =
+  'a[href]:not([tabindex="-1"]), button:not([disabled]):not([aria-disabled="true"]), textarea:not([disabled]):not([aria-disabled="true"]):not([tabindex="-1"]), input:not([disabled]):not([aria-disabled="true"]):not([tabindex="-1"]), select:not([disabled]):not([aria-disabled="true"]):not([tabindex="-1"]), area[href]:not([tabindex="-1"]), iframe:not([tabindex="-1"]), [tabindex]:not([tabindex="-1"]), [contentEditable=true]:not([tabindex="-1"])';
 
 export enum Label {
   Toggle = "Toggle menu",
@@ -73,6 +79,12 @@ export type BaseProps<L> = PropsWithSpread<
      * Whether the dropdown should scroll if it is too long to fit on the screen.
      */
     scrollOverflow?: boolean;
+    /**
+     * Whether to focus the first interactive element within the menu when it opens.
+     * This defaults to true.
+     * In instances where the user needs to interact with some other element on opening the menu (like a text input), set this to false.
+     */
+    focusFirstItemOnOpen?: boolean;
     /**
      * Whether the menu should be visible.
      */
@@ -179,12 +191,14 @@ const ContextualMenu = <L,>({
   toggleLabelFirst = true,
   toggleProps,
   visible = false,
+  focusFirstItemOnOpen = true,
   ...wrapperProps
 }: Props<L>): React.JSX.Element => {
-  const id = useId();
+  const dropdownId = useId();
   const wrapper = useRef<HTMLSpanElement | null>(null);
   const [positionCoords, setPositionCoords] = useState<DOMRect>();
   const [adjustedPosition, setAdjustedPosition] = useState(position);
+  const focusAnimationFrameId = useRef<number | null>(null);
 
   useEffect(() => {
     setAdjustedPosition(position);
@@ -199,23 +213,116 @@ const ContextualMenu = <L,>({
     setPositionCoords(parent.getBoundingClientRect());
   }, [wrapper, positionNode]);
 
+  /**
+   * Gets the dropdopwn element (`ContextualMenuDropdown`).
+   * @returns The dropdown element or null if it does not exist.
+   */
+  const getDropdown = useCallback(() => {
+    if (typeof document === "undefined") return null;
+    /**
+     * This is Using `document` instead of refs because `dropdownProps` may include a ref,
+     * while `dropdownId` is unique and controlled by us.
+     */
+    return document.getElementById(dropdownId);
+  }, [dropdownId]);
+
+  /**
+   * Gets all focusable items in the dropdown element.
+   * @returns Array of focusable items in the dropdown element.
+   */
+  const getFocusableDropdownItems = useCallback(() => {
+    return Array.from(
+      getDropdown()?.querySelectorAll<HTMLElement>(focusableElementSelectors) ||
+        [],
+    );
+  }, [getDropdown]);
+
+  /**
+   * Focuses the first focusable item in the dropdown element.
+   * This is useful for keyboard users (who expect focus to move into the menu when it opens).
+   */
+  const focusFirstDropdownItem = useCallback(() => {
+    const focusableElements = getFocusableDropdownItems();
+    focusableElements[0]?.focus();
+  }, [getFocusableDropdownItems]);
+
+  /**
+   * Cleans up any pending dropdown focus animation frames.
+   */
+  const cleanupDropdownFocus = () => {
+    if (focusAnimationFrameId.current) {
+      cancelAnimationFrame(focusAnimationFrameId.current);
+      focusAnimationFrameId.current = null;
+    }
+  };
+
+  useEffect(() => {
+    return () => cleanupDropdownFocus();
+  }, []);
+
   const { openPortal, closePortal, isOpen, Portal } = usePortal({
     closeOnEsc,
     closeOnOutsideClick,
     isOpen: visible,
-    onOpen: () => {
+    onOpen: (event) => {
       // Call the toggle callback, if supplied.
       onToggleMenu?.(true);
       // When the menu opens then update the coordinates of the parent.
       updatePositionCoords();
+
+      if (
+        focusFirstItemOnOpen &&
+        // Don't focus the item unless it was opened by a keyboard event
+        // This type silliness is because `detail` isn't on the type for `event.nativeEvent` passed from `usePortal`,
+        // as we are using `CustomEvent<HTMLElement>` which does not have `detail` defined.
+        event?.nativeEvent &&
+        "detail" in event.nativeEvent &&
+        event.nativeEvent.detail === 0
+      ) {
+        cleanupDropdownFocus();
+        // We need to wait a frame for any pending focus events to complete.
+        focusAnimationFrameId.current = requestAnimationFrame(() =>
+          focusFirstDropdownItem(),
+        );
+      }
     },
     onClose: () => {
       // Call the toggle callback, if supplied.
       onToggleMenu?.(false);
+      cleanupDropdownFocus();
     },
     programmaticallyOpen: true,
   });
 
+  /**
+   * Trap focus within the dropdown
+   */
+  useEffect(() => {
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if (e.key !== "Tab" || !isOpen) return;
+      const items = getFocusableDropdownItems();
+      if (items.length === 0) return;
+      const active = document.activeElement;
+      const first = items[0];
+      const last = items[items.length - 1];
+      if (!e.shiftKey && active === last) {
+        // Tab on the last item: wrap back to the first focusable item
+        e.preventDefault();
+        first.focus();
+      } else if (e.shiftKey && active === first) {
+        // Shift+Tab on the first item: wrap back to the last focusable item
+        e.preventDefault();
+        last.focus();
+      }
+    };
+    const dropdown = getDropdown();
+    if (!dropdown) return undefined;
+    dropdown.addEventListener("keydown", handleKeyDown);
+    return () => {
+      dropdown.removeEventListener("keydown", handleKeyDown);
+    };
+  }, [getDropdown, getFocusableDropdownItems, isOpen]);
+
   const previousVisible = usePrevious(visible);
   const labelNode =
     toggleLabel && typeof toggleLabel === "string" ? (
@@ -296,7 +403,7 @@ const ContextualMenu = <L,>({
     toggleNode = (
       <Button
         appearance={toggleAppearance}
-        aria-controls={id}
+        aria-controls={dropdownId}
         aria-expanded={isOpen ? "true" : "false"}
         aria-label={toggleLabel ? null : Label.Toggle}
         aria-pressed={isOpen ? "true" : "false"}
@@ -346,7 +453,7 @@ const ContextualMenu = <L,>({
             constrainPanelWidth={constrainPanelWidth}
             dropdownClassName={dropdownClassName}
             dropdownContent={children}
-            id={id}
+            id={dropdownId}
             isOpen={isOpen}
             links={links}
             position={position}

src/components/CustomSelect/CustomSelect.tsx

@@ -178,6 +178,7 @@ const CustomSelect = ({
           .join(" ")}
         aria-errormessage={hasError ? validationId : undefined}
         aria-invalid={hasError}
+        focusFirstItemOnOpen={false}
         toggleClassName={classNames(
           "p-custom-select__toggle",
           "p-form-validation__input",