async-action-intent.js

// Action creators

function savePost( post ) {
	return {
		type: 'SAVE_POST',
		post
	};
}

function receivePost( post ) {
	return {
		type: 'RECEIVE_POST',
		post
	};
}

// Side effects mapping

const effects = {
	SAVE_POST: ( action ) => ( {
		type: 'REQUEST',
		url: '/wp-json/wp/v2/posts',
		params: {
			method: 'POST',
			body: encodeURIComponent( post )
		},
		success: receivePost
	} )	
};

// Middlewares

const effectsMiddleware = ( store ) => ( next ) => ( action ) => {
	if ( effects.hasOwnProperty( action.type ) {
		store.dispatch( effects[ action.type ]( action ) );
	}

	return next( action );
};

const requestMiddleware = ( store ) => ( next ) => ( action ) => {
	if ( 'REQUEST' === action.type ) {
		window.fetch( action.url, action.params )
			.then( ( response ) => response.json() )
			.then( ( data ) => store.dispatch( action.success( data ) ) );
	}

	return next( action );	
};