Updated No-Jquery Allmusic Recs Gist

allmusic-ratings.js

window.addEventListener("load", function(event) {

  var userratingdiv = document.getElementsByClassName("ratings")[0];
  
  const button = document.createElement('a');
  button.setAttribute("id", "rate-button");
  button.innerHTML = '<h3>Rate Album</h3>'
  userratingdiv.insertBefore(button, userratingdiv.firstChild)
  	
  var userratingbutton = document.getElementById("rate-button");

  userratingbutton.setAttribute("role", "button");
  userratingbutton.setAttribute("tabindex",0);
  setarialabel();
  userratingbutton.addEventListener("click", setmyrating, false);

});

	
function setmyrating(){
    var arialabel = setarialabel();
    var userratingdiv = document.getElementsByClassName("album-page-user-rating")[0];

    var dataid = userratingdiv.getAttribute('data-id');

    var rating = prompt(arialabel+'\nRate this album, 1-10: ');

    var modrating = parseInt(rating,10)*10;

    var httpRequest = new XMLHttpRequest();
    httpRequest.onreadystatechange = function (data) {
       console.log('Saved Rating');
    }
    var saveurl = 'https://www.allmusic.com/rating/save';
    httpRequest.open('POST', saveurl);
    httpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    httpRequest.send('id='+encodeURIComponent(dataid)+'&score='+encodeURIComponent(modrating));

    var allclasses = userratingdiv.className.split(' ');
    var ratingclass = allclasses.find(a =>a.includes("rating-user-"));

    userratingdiv.setAttribute("aria-label", 'My Rating: '+rating);
    userratingdiv.classList.remove(ratingclass)
    if(rating < 10) {
    	rating = '0'+rating;
    }
	userratingdiv.classList.add("rating-user-"+rating)
}

function setarialabel() {
    
    var userratingdiv = document.getElementsByClassName("album-page-user-rating")[0];

    var arialabel = '';
    var allclasses = userratingdiv.className.split(' ');
    var ratingclass = allclasses.find(a =>a.includes("rating-user-"));

    if(undefined != ratingclass) {

       var rating = ratingclass.replace("rating-user-", "");
       if(rating == 0) {
           arialabel = 'My Rating: Not Yet Rated';
       } else {
         arialabel = 'My Rating: '+rating;
       }

    } else {
       arialabel = 'My Rating: Not Yet Rated';
    }

    userratingdiv.setAttribute("aria-label", arialabel)
  
    return arialabel;
}