babel-plugin-async-load.js

export default function( babel ) {
	return {
		visitors: {
			CallExpression( path ) {
				if ( 'MemberExpression' !== path.callee.type ||
						'React' !== path.callee.object.name ||
						'createElement' !== path.callee.property ||
						path.arguments.length < 2 ||
						'Identifier' !== path.arguments[ 0 ].type ||
						'AsyncLoad' !== path.arguments[ 0 ].name ) {
					return;
				}

				const requireProperty = path.arguments[ 1 ].properties.find( ( property ) => {
					return 'require' === property.key.name;
				} );

				if ( ! requireProperty ) {
					return;
				}

				const module = requireProperty.value.value;
				requireProperty.value.replaceWithSourceString(
					`function( callback ) {
						require.ensure( '${ module }', function() {
							callback( require( '${ module }' ) );
						} );
					}`
				);
			}
		}
	};
}