function fetch(url, id) {
  var req = new XMLHttpRequest();
  req.onload = function() {
    var element = document.getElementById(id);
    var node = document.createElement("div");
    node.innerHTML = this.response;
    element.appendChild(node);
  };
  req.open("GET", url);
  req.send();
}

window.onload = function() {
  var num_members = 0;
  var num_songs = 0;

  var add_member_button = document.getElementById('add-member-button');
  var add_song_button = document.getElementById('add-song-button');

  add_member_button.onclick = function() {
    num_members += 1;
    fetch(window.location + '/member/new/' + num_members, 'form-members');
  };

  add_song_button.onclick = function() {
    num_songs += 1;
    fetch(window.location + '/song/new/' + num_songs, 'form-songs');
  };
};