javascript实现ecshop搜索框键盘上下键切换控制

/* 键盘操作与问题推荐选择 */
    var curDo = null;
    var select = createSelect();
    $('#keywords').keyup(function(e){
        var theEvent =  e || window.event;
        code = theEvent.keyCode ? theEvent.keyCode : (theEvent.which ? theEvent.which : theEvent.charCode)
        var KEY = {
            UP: 38,
            DOWN: 40,
            DEL: 46,
            TAB: 9,
            RETURN: 13,
            ESC: 27,
            BACKSPACE: 8,
            LEFT:37,
            RIGHT:39
        };
        clearTimeout(curDo);//键盘弹起的时候应该取消定时ajax获取数据操作
        switch(code) {
            case KEY.UP:
                select.next();
                break;
            case KEY.DOWN:
                select.prev();
                break;
            case KEY.RETURN:
                $('.suggest-hover').trigger('click');
                break;
            case KEY.LEFT:
                break;
            case KEY.RIGHT:
                break;
            default:
                curDo = setTimeout(getSuggest(),300);
                break;
        }
    });
/* suggest选择操作 */
    function createSelect(){
        var CLASSES = {
            ACTIVE: "suggest-hover"
        };
        function moveSelect(step) {
            var listItems=$('.suggest-results li');
            //当前hover的步数
            var active;
            active =  $('.'+CLASSES.ACTIVE).index();
            listItems.eq(active).removeClass(CLASSES.ACTIVE);
            active += step;
            if (active < 0) {
                active = listItems.size() - 1;
            } else if (active >= listItems.size()) {
                active = 0;
            }
            var activeItem = listItems.eq(active).addClass(CLASSES.ACTIVE);
        };
        return {
            next:function(){
                moveSelect(-1);
            },
            prev:function(){
                moveSelect(1);
            }
        };
    };