基于jquery如何实现的自动补全功能

$(function() {
    // 自动补全
    var maxcount = 0;// 表示他最大的值
    var thisCount =0;// 初始化他框的位置
    $("body").prepend("<div style='width:120px; display:none; background:#FFFFFF; position: absolute;' id='autoTxt'></div>");
    $("#sele").keyup(function(even) {
        var v = even.which;
        if (v == 38 || v == 40 || v == 13)// 当点击上下键或者确定键时阻止他传送数据
            {
            return;
            }
        var txt = $("#sele").val();//这里是取得他的输入框的值
        if (txt != "") {
            //拼装数据
            $.ajax({
                url : "Birthday_autoCompletion",//从后台取得json数据
                type : "post",
                dataType : "json",
                data : {"bir.userName" : txt
                },
                success : function(ls) {
                    var offset = $("#sele").offset();
                    $("#autoTxt").show();
                    $("#autoTxt").css("top", (offset.top + 30) + "px");
                    $("#autoTxt").css("left", offset.left + "px");
                    var Candidate = "";
                     maxcount = 0;//再重新得值
                    $.each(ls, function(k, v) {
                        Candidate += "<li id='" +maxcount+ "'>" + v + "</li>";
                        maxcount++;
                    });
                    $("#autoTxt").html(Candidate);
                    $("#autoTxt li:eq(0)").css("background", "#A8A5A5");
                    //高亮对象
                    $('body').highLight();
                    $('body').highLight($("#sele").val());
                    event.preventDefault();
                        //当单击某个ＬＩ时反映
                        $("#autoTxt li").click(function(){
                            $("#sele").val($("#autoTxt li:eq("+this.id+")").text());
                            $("#autoTxt").html("");
                            $("#autoTxt").hide();
                        });
                        //移动对象
                        $("#autoTxt li").hover(function(){
                            $("#autoTxt li").css("background", "#FFFFFF");
                            $("#autoTxt li:eq("+this.id+")").css("background", "#A8A5A5");
                            thisCount=this.id;},function(){
                                $("#autoTxt li").css("background", "#FFFFFF");});
                },
                error : function() {
                    $("#autoTxt").html("");
                    $("#autoTxt").hide();
                    maxcount = 0;
                }
            });
        } else {
            $("#autoTxt").hide();
            maxcount = 0;
            $("#sestart").click();
        }
    });
    //当单击ＢＯＤＹ时则隐藏搜索值
    $("body").click(function(){
        $("#autoTxt").html("");
        $("#autoTxt").hide();
        thisCount=0;
    });
    // 写移动事件//上键３８ 下键４０ 确定键 １３
    $("body").keyup(function(even) {
        var v = even.which;
            if (v == 38)// 按上键时
            {
                if(thisCount!=0){//等于零时则证明不能上了。所以获得焦点
                    $("#sele").blur();
                    if(thisCount>0)
                        --thisCount;
                    else
                        thisCount=0;
                $("#autoTxt li").css("background", "#FFFFFF");
                $("#autoTxt li:eq("+thisCount+")").css("background", "#A8A5A5");
                }else{$("#sele").focus();}
            } else if (v == 40) {// 按下键时
                if(thisCount<maxcount-1)
                {
                    $("#sele").blur();
                    ++thisCount;
                    $("#autoTxt li").css("background", "#FFFFFF");
                    $("#autoTxt li:eq("+thisCount+")").css("background", "#A8A5A5");
                }
            } else if (v == 13) {// 按确认键时
                var tt=$("#"+thisCount).text();
                if(tt!="")
                    {
                        $("#sele").val(tt);
                        $("#autoTxt").html("");
                        $("#autoTxt").hide();
                    }else
                    {
                        if($("#sele").val()!="")
                        $("#sestart").click();
                    }
            } else {
                if($("#autoTxt").html()!="")
                    {
                        $("#sele").focus();
                        thisCount=0;
                    }
            }
    });
});