How do I get the id of the control calling the jquery autocomplete function?

I want to use the jquery autocomplete plugin across several input boxes. In order to keep my code DRY I want to tie the autocomplete function to a class and within the autocomplete function pass the id of the field that has called it as an extra parameter. What I am struggling with is obtaining the id of the field that has called the function. Example code of what I am doing is below; can anyone see the problem?

        $(".className").autocomplete('<%=Url.Action("Method", "Controller") %>', {
            dataType: 'json',
            parse: function(data) {
                var rows = new Array();
                for (var i = 0; i < data.length; i++) {
                    rows[i] = { data: data[i], value: data[i], result: data[i] };
                }
                return rows;
            },
            formatItem: function(row) {
                return row;
            },
            extraParams: {
                extra: function() {
                    var Field1 = $(this).attr('id');
                    var Field2 =  $("#Field1").val();
                    var Field2 =  $("#Field2").val();
                    var Field3 =  $("#Field3").val();
     开发者_JAVA技巧               return Field1 + "$" + Field2 + "$" + Field3 + "$" + Field4; 
                 }
            },
            delay: 40,
            autofill: true,
            selectFirst: false,
            multiple: false
        });

Are you sure this is passed to your extraParams function? If not then you can use something like:

$(".className").each(function(){
   var el = $(this);
   .....
       extra: function() {
            var Field1 = el.attr(id);
       }
});

This will allow you to tie each autocomplete to its own specific element.