 
 valid_file = (filename) ->
   extension = filename.substr(filename.lastIndexOf('.'), filename.length)
-  $.inArray(extension, image_exts) || $.inArray(extension, doc_exts)
+  image_exts.includes(extension) || doc_exts.includes(extension)
 
 add_to_file_list = (filename, url, markdown_url) ->
   unhide_file_list()

        data.progress_bar = $('<progress max="100" value="0" class="image-upload">').insertAfter($('.attach-files'))
        data.label = $('<label>').insertAfter(data.progress_bar)
        try
          unless valid_file(data.files[0].name)
            handle_file_error(data)
          if data.files[0].name
            data.orig_name = data.files[0].name
          else
            data.orig_name = 'image'
          data.submit().error (e) ->
            handle_file_error(data)
    progress: (e, data) ->
      percent = parseInt(data.loaded / data.total * 100, 10)
      if percent < 99

      data.label.remove()
      src = data.result.source
      extension = src.url.substr(src.url.lastIndexOf('.'), src.url.length)
      if image_exts.includes(extension)
        add_to_file_list(data.orig_name, src.url, image_markdown(remove_ext(data.orig_name), src.url))
      else
        add_to_file_list(data.orig_name, src.url, link_markdown(remove_ext(data.orig_name), src.url))
