Creating a notice in Gutenberg

index.js

// See https://github.com/WordPress/gutenberg/blob/master/docs/designers-developers/developers/tutorials/notices/README.md

const {
	dispatch,
} = wp.data;

const {
	createWarningNotice,
} = dispatch( 'core/notices' );

createWarningNotice(
	'Warning message',
	{
		isDismissible: false,
		id: 'warningmessage',
		actions: [
			{
				url: 'https://google.com',
				label: 'This is a URL',
			},
			{
				label: 'This is a button',
				onClick: ( s ) => { console.log( s, 'this' ); },
				className: 'custom_classname',
			},
		],
	}
);