block.js

const Display = (props)  => (
	<div>{props.whatever}</div>
);

registerBlockType(
	"hi/roy",
	{
		//...
		edit({ attributes, setAttributes }) {

			return (
				<Fragment>
					<InspectorControl>
						<TextControl value={attributes.whatever} onChange={(whatever) => setAttributes({whatever})} />
					</InspectorControl>
					<Display {...attributes} />
				</Fragment>
			);
		},

		save({ attributes }) {
			<Display {...attributes} />
		}
	}
);