Example to add external react and react-dom library in Next.js using CDN

next.config.js

module.exports = {
     webpack: (config, options) => {
         const { isServer, webpack } = options;
         if (isServer) {
          // Use the react from node_modules
         } else {
          config.externals = {
            react: 'React',
            'react-dom': 'ReactDOM',
            };
         }
     }
}