jquery控制层不超出屏幕范围

$(document).ready(function(){
    var _lll= $(window).width();
    var _mmm = 0;
    $(".valuation li img").mouseover(function(e){
        titles=$(this).attr("title");
        $(this).attr("title","");        
        $(".valuation li").append("<div class='valtip'>"+titles+"</div>");        
        var _kkk= $(this).position().left;
        var _jjj= $(".valtip").width()+84;        
        if(e.pageX+10+_jjj>=_lll){
            _mmm=_lll-_jjj-10;
        }
        else{
        _mmm =e.pageX+10;
        }
        $(".valtip").css({"top":(e.pageY+10)+"px","left":(_mmm)+"px"});
    }).mousemove(function(e){
        var _kkk= $(this).position().left;
        var _jjj= $(".valtip").width()+84;
        if(e.pageX+20+_jjj>=_lll){
            _mmm=_lll-_jjj-10;
        }
        else{
        _mmm =e.pageX+10;        
        }
        $(".valtip").css({"top":(e.pageY+10)+"px","left":(_mmm)+"px"});
        
    }).mouseout(function(){
        $(".valtip").remove();
        $(this).attr("title",titles);
        })
        $(window).bind("resize",function(){
        _lll=$(window).width();
        }); 
})