search filter

<=== HTMLnya ===>
<input id="keyword_filter" name="keyword" type="text" autocomplete="off" class="input-lg">

<=== Javascriptnya ===>
$(function () {
    $("#results").hide();
    var base_url = window.location.origin;
    var select = document.getElementById("pilihkategori");
    var selected = select.options[select.selectedIndex].value;
    if (selected == 1) {
        $("#keyword_filter").on('keyup' , function() {
            console.log(this.value);
            var search = $(this).val();
            if (search.length > 3) {
                $.ajax({
                    url: base_url + '/buku/semuabuku/' + search,
                    type:'GET',
                    data:'keyword='+search,
                    beforeSend:function () {
                        $("#results").slideUp('fast');
                    },
                    success:function (data) {
                        $("#results").html(data);
                        $("#results").slideDown('fast');
                    }
                });
            } else if (search.length < 3) {
                $("#results").hide();
            }
        });
    } else {
        $('#pilihkategori').change(function(){
            var id_kategori = $(this).val();
            console.log(id_kategori);

            $.ajax({
                url: base_url + '/buku/bykategori/' + id_kategori,
                type:'GET',
                data:'keyword='+search,
                beforeSend:function () {
                    $("#results").slideUp('fast');
                },
                success: function(data) {
                    console.log(data);
                    $('#keyword_filter').on('keyup', function () {
                        var kata = $(this).val();
                        if (kata.length > 3) {
                            $("#results").html(data);
                            $("#results").slideDown('fast');
                        } else $("#results").hide();
                    });
                }
            });
        });
    }
});