How to refresh w2ui grid on dropdown menu index change?

    function onSelectedIndexChange()
   {
    //prepare records using loop
   
    try
     {
          w2ui['grid']. destroy ();
     }
     catch(ex){}

    defineGrid(); // call the function to define grid columns and other properties
    w2ui['grid'].records = listData;
    w2ui['grid'].refresh();
    }