test HEAD

gistfile1.txt

const testHEAD = function(url) {
  var xmlhttp = new XMLHttpRequest();
  xmlhttp.open("HEAD", url, true); 
  xmlhttp.onreadystatechange=function() {
     if(xmlhttp.readyState==4) { 
       console.log(xmlhttp.getAllResponseHeaders());
     }
  }
  xmlhttp.send(null); 
}