Filtering

<input id="combobox" />
<script>
$("#combobox").kendoComboBox({
  dataSource: [ "Apples", "Oranges" ],
  filter: "startswith",
  filtering: function(e) {
      //get filter descriptor
      var filter = e.filter;

      // handle the event
  }
});
</script>

<input id="combobox" />
<script>
function combobox_filtering(e) {
  //get filter descriptor
  var filter = e.filter;

  // handle the event
}
$("#combobox").kendoComboBox({
  dataSource: [ "Apples", "Oranges" ],
  filter: "startswith"
});
var combobox = $("#combobox").data("kendoComboBox");
combobox.bind("filtering", combobox_filtering);
</script>

<input id="combobox" />
<script>
$("#combobox").kendoComboBox({
  dataSource: [ "Apples", "Oranges" ],
  filter: "startswith",
  filtering: function(e) {
      var filter = e.filter;

      if (filter && !filter.value) {
        //prevent filtering if the filter does not value
        e.preventDefault();
      }
  }
});
</script>