asp.net ajaxtoolkit autocomplete CompletionListItemCssClass change int javascript

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ASP.NET

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Hello...
I created a dictionary and I used ajaxtoolkit autocompele to suggest word when I write it in the text box but the suggestion just show in left side of the suggestion box I need to change

CompletionListItemCssClass 

and I want to how to do this in javascript this my code:
ajaxtoolkit:

<asp:AutoCompleteExtender ID="autocom"  ClientIDMode="Static"  runat="server" CompletionSetCount="10" CompletionListElementID="list"   CompletionListItemCssClass="toolkitEnglish"
                EnableCaching="true" MinimumPrefixLength="1" TargetControlID="txtBoxWord"   ServicePath="~/translator/AutoComplete.asmx" ServiceMethod="GetCompletionList"  >

            </asp:AutoCompleteExtender>

this javascript code:

<script type="text/javascript">
          var index = 0;
          function IndexChanged() {
              index = comboboxLang.GetSelectedIndex();
              if (index == 0) {
                  $("#txtBoxWord").css("direction", "ltr");
                  $("#txtBoxWord").val("");
                  $find('autocom').set_contextKey("1");
                  $find('list').set_CompletionListItemCssClass("toolkitEnglish");

                  //$("#list").removeClass("toolkitKurdish");

                  //$("#list").addClass("toolkitEnglish");
              }
              if (index == 1) {
                  $("#txtBoxWord").css("direction", "rtl");
                  $("#txtBoxWord").val("");
                 
                  $find('autocom').set_contextKey("2");
                  $find('list').set_CompletionListItemCssClass("toolkitKurdish");

                  //$("#list").removeClass("toolkitEnglish");
                  //$("#list").addClass("toolkitKurdish");

              }
          }

            </script>