JQuery：为什么我得到一个未捕获的TypeError：无法设置属性＆＃39; _renderItem＆＃39;未定义的

Question

此代码应该使用ISBN或书名，并针对googles book API运行，返回有效结果。代码似乎独立工作，但当我们将它放入我们的Dreamfactory服务器时，它返回它无法设置属性＆＃39; _renderItem＆＃39;未定义的。

<script src="https://code.jquery.com/jquery-3.1.1.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
 $(function() {
 $("#txtBookSearch").autocomplete({
  source: function(request, response) {
    var booksUrl = "https://www.googleapis.com/books/v1/volumes?printType=books&maxResults=20&q=" + encodeURIComponent(request.term);
    $.ajax({
      url: booksUrl,
      dataType: "jsonp",
      success: function(data) {
        response($.map(data.items, function(item) {
          if (item.volumeInfo.authors && item.volumeInfo.title && item.volumeInfo.industryIdentifiers && item.volumeInfo.publishedDate) {
            return {
              // label value will be shown in the suggestions
              ebook: (item.saleInfo.isEbook == null ? "" : item.saleInfo.isEbook),
              title: item.volumeInfo.title,
              id: item.id,
              author: item.volumeInfo.authors[0],
              authors: item.volumeInfo.authors,
              isbn: item.volumeInfo.industryIdentifiers,
              publishedDate: item.volumeInfo.publishedDate,
              image: (item.volumeInfo.imageLinks == null ? "" : item.volumeInfo.imageLinks.thumbnail),
              small_image: (item.volumeInfo.imageLinks == null ? "" : item.volumeInfo.imageLinks.smallThumbnail)


            };
          }
        }));
      }
    });
  },
  select: function(event, ui) {
    location.assign("results.html?id=" + ui.item.id);

    },

  delay: 600,
  minLength: 2,
  focus: function(event, ui) {
    event.preventDefault();
  }
});

$("#txtBookSearch").data("ui-autocomplete")._renderItem = function(ul, item) {
  var img = $('<image class="imageClass" src=' + item.small_image + ' alt= n/a' + '/>');
  var link = $('<a>' + item.title + ', ' + item.author + ', ' + item.publishedDate + (item.ebook == "" ? "" : ', (Ebook version)') + '</a>');
  return $('<li>')
    .append("<div>" + img.prop("outerHTML") + link.prop("outerHTML") + "</div>")
    .appendTo(ul);
};
});