Fix:Mentions options does not automatically scroll when navigating through options using the keyboard if the options list is long

src/DropdownMenu.tsx

@@ -1,8 +1,8 @@
-import Menu, { MenuItem } from '@rc-component/menu';
-import * as React from 'react';
+import Menu, { MenuItem, MenuRef } from '@rc-component/menu';
+import React, { useEffect, useRef } from 'react';
 import MentionsContext from './MentionsContext';
 import type { DataDrivenOptionProps } from './Mentions';
-interface DropdownMenuProps {
+export interface DropdownMenuProps {
   prefixCls?: string;
   options: DataDrivenOptionProps[];
 }
@@ -24,9 +24,26 @@ function DropdownMenu(props: DropdownMenuProps) {
 
   const { prefixCls, options } = props;
   const activeOption = options[activeIndex] || {};
+  const menuRef = useRef<MenuRef>(null);
+
+  // Monitor the changes in ActiveIndex and scroll to the visible area if there are any changes
+  useEffect(() => {
+    if (activeIndex === -1 || !menuRef.current) {
+      return;
+    }
+
+    const activeItem = menuRef.current?.findItem?.({ key: activeOption.key });
+    if (activeItem) {
+      activeItem.scrollIntoView({
+        block: 'nearest',
+        inline: 'nearest',
+      });
+    }
+  }, [activeIndex, activeOption.key]);
 
   return (
     <Menu
+      ref={menuRef}
       prefixCls={`${prefixCls}-menu`}
       activeKey={activeOption.key}
       onSelect={({ key }) => {

tests/DropdownMenu.spec.tsx

@@ -0,0 +1,52 @@
+import React from 'react';
+import { render, fireEvent } from '@testing-library/react';
+import Mentions, { UnstableContext } from '../src';
+import { expectMeasuring } from './util';
+
+describe('DropdownMenu', () => {
+  // Generate 20 options for testing scrolling behavior
+  const generateOptions = Array.from({ length: 20 }).map((_, index) => ({
+    value: `item-${index}`,
+    label: `item-${index}`,
+  }));
+
+  // Setup component with UnstableContext for testing dropdown behavior
+  const { container } = render(
+    <UnstableContext.Provider value={{ open: true }}>
+      <Mentions defaultValue="@" options={generateOptions} />
+    </UnstableContext.Provider>,
+  );
+
+  it('should scroll into view when navigating with keyboard', () => {
+    // Mock scrollIntoView since it's not implemented in JSDOM
+    const scrollIntoViewMock = jest
+      .spyOn(HTMLElement.prototype, 'scrollIntoView')
+      .mockImplementation(jest.fn());
+
+    // Press ArrowDown multiple times to make options overflow the visible area
+    for (let i = 0; i < 10; i++) {
+      fireEvent.keyDown(document.activeElement!, { key: 'ArrowDown' });
+    }
+
+    // Verify if scrollIntoView was called
+    expect(scrollIntoViewMock).toHaveBeenCalledWith({
+      block: 'nearest',
+      inline: 'nearest',
+    });
+
+    // Press ArrowUp to verify scrolling up
+    for (let i = 0; i < 5; i++) {
+      fireEvent.keyDown(document.activeElement!, { key: 'ArrowUp' });
+    }
+
+    // Verify if scrollIntoView was called again
+    expect(scrollIntoViewMock).toHaveBeenCalledWith({
+      block: 'nearest',
+      inline: 'nearest',
+    });
+
+    expectMeasuring(container);
+
+    scrollIntoViewMock.mockRestore();
+  });
+});

tests/setup.ts

@@ -4,3 +4,5 @@ global.ResizeObserver = class ResizeObserver {
   unobserve() {}
   disconnect() {}
 };
+
+window.HTMLElement.prototype.scrollIntoView = jest.fn();