> const client = new XMLHttpRequest();
client.open("GET", "http://rolfrost.de/", true);
client.send();
client.onreadystatechange = () => {
  if (client.readyState === client.HEADERS_RECEIVED) {
    const httpLM = client.getResponseHeader("Last-Modified");   
	console.log(httpLM);	
  }
};

<. () => {
  if (client.readyState === client.HEADERS_RECEIVED) {
    const httpLM= client.getResponseHeader("Last-Modified");   
	console.log(httpLM);	
  }
}

VM42:7 Tue, 14 Nov 2023 09:03:16 GMT