how to get dropdown id in Jquery

// try this code
//it will get all dropdown and their values, you can use according to your requirements. 
$("select").each(function(e,i){   alert(e+$(i).val()); });

//e: it will be index of dropdownlist
//i: it is current dropdownlist

//here is code for id
$("select").each(function(e,i){   alert(e+$(i).attr("id")); });//it will get each dropdown index and id

//get id on change of dropdownlist.
$("select").change(function()
  {
   alert(this.id);
  }
);