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();
});
})