discourse/app/assets/javascripts/discourse/dialects/quote_dialect.js

var esc = Handlebars.Utils.escapeExpression;

Discourse.BBCode.register('quote', {noWrap: true, singlePara: true}, function(contents, bbParams, options) {
  var params = {'class': 'quote'},
      username = null;

  if (bbParams) {
    var paramsSplit = bbParams.split(/\,\s*/);
    username = paramsSplit[0];

    paramsSplit.forEach(function(p,i) {
      if (i > 0) {
        var assignment = p.split(':');
        if (assignment[0] && assignment[1]) {
          var escaped = esc(assignment[0]);
          // don't escape attributes, makes no sense
          if(escaped === assignment[0]) {
            params['data-' + assignment[0]] = esc(assignment[1].trim());
          }
        }
      }
    });
  }

  var avatarImg;
  var postNumber = parseInt(params['data-post'], 10);
  var topicId = parseInt(params['data-topic'], 10);

  if (options.lookupAvatarByPostNumber) {
    // client-side, we can retrieve the avatar from the post
    avatarImg = options.lookupAvatarByPostNumber(postNumber, topicId);
  } else if (options.lookupAvatar) {
    // server-side, we need to lookup the avatar from the username
    avatarImg = options.lookupAvatar(username);
  }

  // If there's no username just return a simple quote
  if (!username) {
    return ['p', ['aside', params, ['blockquote'].concat(contents)]];
  }

  var header = [ 'div', {'class': 'title'},
                 ['div', {'class': 'quote-controls'}],
                 avatarImg ? ['__RAW', avatarImg] : "",
                 username ? I18n.t('user.said', {username: username}) : ""
               ];

  if (options.topicId && postNumber && options.getTopicInfo && topicId !== options.topicId) {
    var topicInfo = options.getTopicInfo(topicId);
    if (topicInfo) {
      var href = topicInfo.href;
      if (postNumber > 0) { href += "/" + postNumber; }
      // get rid of username said stuff
      header.pop();
      header.push(['a', {'href': href}, topicInfo.title]);
    }
  }


  return ['aside', params, header, ['blockquote'].concat(contents)];
});