Building Accessible Multilevel Dropdown Menus in React

Understanding the Basics

Before we dive into the implementation, let’s break down the components of our multilevel dropdown menu:

• App: The parent component that renders the header and navigation bar.
• Header: The component that contains the logo and navigation bar.
• Navbar: The component that renders the menu items.
• MenuItems: The component that renders individual menu items and their corresponding dropdowns.
• Dropdown: The component that renders the submenu items.

Setting Up the Project

To get started, create a new React project using the create-react-app CLI. Then, create the necessary folders and files for our components.

npx create-react-app my-app
cd my-app
mkdir components
touch components/App.js components/Header.js components/Navbar.js components/MenuItems.js components/Dropdown.js

Rendering Top-Level Menu Items

Let’s start by rendering the top-level menu items. Create a menuItemsData.js file to hold the menu item data.

export const menuItemsData = [
  { id: 1, label: 'Home' },
  { id: 2, label: 'About' },
  { id: 3, label: 'Services' },
  { id: 4, label: 'Contact' },
];

Then, update the Navbar component to render the menu items.

import React from 'eact';
import menuItemsData from './menuItemsData';

const Navbar = () => {
  return (

{menuItemsData.map((menuItem) => (
• {menuItem.label}

))}

  );
};

export default Navbar;

Rendering a Single-Level Dropdown Menu

Next, let’s add a single-level dropdown menu to our navigation bar. Update the menuItemsData.js file to include a submenu for the Services link.

export const menuItemsData = [
  { id: 1, label: 'Home' },
  { id: 2, label: 'About' },
  {
    id: 3,
    label: 'Services',
    submenu: [
      { id: 31, label: 'Service 1' },
      { id: 32, label: 'Service 2' },
    ],
  },
  { id: 4, label: 'Contact' },
];

Then, modify the Navbar component to render the dropdown menu.

import React from 'eact';
import menuItemsData from './menuItemsData';

const Navbar = () => {
  return (

{menuItemsData.map((menuItem) => (
• {menuItem.label}
  {menuItem.submenu && (
  {menuItem.submenu.map((submenuItem) => (
  • {submenuItem.label}

  ))}

  )}

))}

  );
};

export default Navbar;

Adding Multilevel Dropdown Menu Components

To add multilevel dropdown menu components, we’ll recursively render the menu items. Update the Dropdown component to delegate the rendering of menu items to the MenuItems component.

import React from 'eact';
import MenuItems from './MenuItems';

const Dropdown = ({ menuItems }) => {
  return (

{menuItems.map((menuItem) => (

))}

  );
};

export default Dropdown;

Detecting the Menu Depth Level

To detect the menu depth level, we’ll add a depthLevel prop to the MenuItems component.

import React from 'eact';
import Dropdown from './Dropdown';

const MenuItems = ({ menuItem, depthLevel = 0 }) => {
  return (

    

      {menuItem.label}
      {menuItem.submenu && (
        
      )}



  );
};

export default MenuItems;

Closing the Dropdown Menu on Click Outside

To close the dropdown menu when the user clicks outside of it, we’ll use the useEffect and useRef Hooks to detect clicks outside of the dropdown menu.

import React, { useEffect, useRef } from 'eact';

const Dropdown = ({ menuItems }) => {
  const dropdownRef = useRef(null);

  useEffect(() => {
    const handleClickOutside = (event) => {
      if (!dropdownRef.current.contains(event.target)) {
        // Close the dropdown menu
      }
    };
    document.addEventListener('click', handleClickOutside);
    return () => {
      document.removeEventListener('click', handleClickOutside);
    };
  }, [dropdownRef]);

  return (

{menuItems.map((menuItem) => (

))}

  );
};

export default Dropdown;

Implementing Routing

To implement routing, we’ll use the React Router library.

import React from 'eact';
import { BrowserRouter, Route, Link } from 'eact-router-dom';

const App = () => {
  return (
    
      
      
      
      
    
  );
};

export default App;

Making the Multilevel Dropdown Responsive

To make the multilevel dropdown responsive, we’ll create a MobileNav component that will be rendered on smaller screens.

import React from 'eact';

const MobileNav = () => {
  return (

  );
};

export default MobileNav;

Optimizing Dropdown Menu Performance

To optimize dropdown menu performance, we can implement lazy loading, responsive design, minimize animations and transitions, and efficient data fetching and caching.

• Use lazy loading to load menu items only when needed.
• Implement responsive design to adapt to different screen sizes.
• Minimize animations and transitions to improve performance.
• Use efficient data fetching and caching to reduce server requests.