class SPARQLQueryDispatcher {
	constructor( endpoint ) {
		this.endpoint = endpoint;
	}

	query( sparqlQuery ) {
		const fullUrl = this.endpoint + '?query=' + encodeURIComponent( sparqlQuery );
		const headers = { 'Accept': 'application/sparql-results+json' };

		return fetch( fullUrl, { headers } ).then( body => body.json() );
	}
}

const endpointUrl = '{ENDPOINT_URL}';
const sparqlQuery = {SPARQL_QUERY};

const queryDispatcher = new SPARQLQueryDispatcher( endpointUrl );
queryDispatcher.query( sparqlQuery ).then( console.log );