<script type="text/javascript">
      
  var a1;
 jQuery(function() {
  a1 = $('#comuni').autocomplete({
      width: 150,
      delimiter: /(,|;)\s*/,
      lookup: 'Roma,Milano,Firenze,Bari,Napoli,Venezia,Verona,Forlì,Torino'.split(',')
    });
 });

</script>

[...]

<input type="text" name="q" id="comuni" class="textbox" />

Protected comuni As New ArrayList()

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim cn As New MySqlConnection(cntxt)
        'Oggetto command per mysql 
        Dim cm As New MySqlCommand("SELECT nome FROM comuni", cn)
        Dim mydata As New DataTable

        [...]

        Dim count As Integer
        count = mydata.Rows.Count

        For i As Integer = 0 To count - 1
            comuni.Add(mydata.Rows(i).ItemArray)
        Next
        
    End Sub

var comuni = [];
comuni[0] = '<%=comuni(0)%>';