wp-calypso/client/components/async-load/index.tsx

import { lazy, useMemo, Suspense, type ComponentType, type ReactNode } from 'react';

import './style.scss';

const DEFAULT_PLACEHOLDER = <div className="async-load__placeholder" />;

type AsyncLoadProps = {
	placeholder?: ReactNode;
	require: string;
	[ key: string ]: unknown;
};

type RequireCallback = () => Promise< { default: ComponentType } >;

export default function AsyncLoad( {
	placeholder = DEFAULT_PLACEHOLDER,
	require,
	...props
}: AsyncLoadProps ) {
	const Component = useMemo( () => {
		// The string is transformed to a function by the `wpcalypso-async` Babel transform
		const requireCb = require as unknown as RequireCallback;
		return lazy( requireCb );
	}, [ require ] );

	return (
		<Suspense fallback={ placeholder }>
			<Component { ...props } />
		</Suspense>
	);
}