anchor.diff:    // The [revert] button is available only from the review *dialog*.
     //---------------------------------------------------------------------
   
  -  cd.setReviewDialogData = function(id, avatar, wasTag, nowTag, filename) {
  -    param = {
  -      id:id,
  -      avatar:avatar,
  -      wasTag:wasTag,
  -      nowTag:nowTag,
  -      filename:filename
  -    };
  -    reviewRefresh();
  -  };
  -
  -  var param = {
  +  let param = {
             id: "<%= @kata.id %>",
         avatar: "<%= @avatar.name %>",
         wasTag: "<%= @was_tag %>",
  
positive.code:   // refresh [<] avatar [>]
    //-----------------------------------------
  
    var refreshAvatarControls = function() {
      refreshPrevAvatarHandler();
      refreshAvatarImage();
      refreshNextAvatarHandler();
    };
  
    var refreshAvatarImage = function() {
      $('#avatar').parent().html(makeAvatarImageHtml());
    };
  
    var makeAvatarImageHtml = function() {
      return '<img id="avatar" src="/images/avatars/' + param.avatar + '.jpg"/>';
    };
  
    var refreshPrevAvatarHandler = function() {
      refreshAvatarHandler('prev', param.prevAvatar);
    };
  
    var refreshNextAvatarHandler = function() {
      refreshAvatarHandler('next', param.nextAvatar);
    };
  
    var refreshAvatarHandler = function(id, name) {
      var title = function() {
        var text = 'Click to review ' + name + "'s ";
        return text + (inDiffMode() ? 'diffs' : 'current code');
      };
      $('#' + id + '-avatar')
        .attr('disabled', name == '')
        .attr('title', title())
        .unbind('click')
        .bind('click', function() {
          param.avatar = name;
          if (inDiffMode()) {
            show(1);
  
negative.code: 
    // - - - - - - - - - - - - - - - - - - - - - - - -
  
    const makeDiffFilenames = (diffs) => {
      // align-right is for diff toggling added/deleted line counts
      return '' +
        '<table align="right">' +
  