let btn = document.getElementById("call_fetch_btn");
btn.addEventListener("click", wakeUpFetch);

function wakeUpFetch() {
	// Try it with other ressources to evoke an error:
	fetch("resources/resource.php")
	.then((response) => {
		// Check the HTTP-Status of the response
		if (!response.ok) {
          	throw new Error('HTTP error, status = ' + response.status + ' - Ressource hat nicht geantwortet');
        }
        else {
        	// Check the Content-Type in the header of the response
        	const ContentType = response.headers.get('content-type');
        	const isContentTypeCorrect = ContentType.includes('application/json');
        	if (!isContentTypeCorrect) {
        		throw new Error('Der Content-Type ist: ' + ContentType + ' - Leider kein JSON');
        	}
        	else {
        	 	return response.json();
        	}
        }
    })
	.then((data) => console.log("Resultat: ", data.a))
	// Error-Spaghetti 
	.catch((error) => {
  		console.log('Es gab einen Fehler!', error)
	});
}