判断鼠标从哪个方向进入--jQuery

$("#wrap").bind("mouseenter mouseleave",function(e) {
       var w = $(this).width();
       var h = $(this).height();
           var x = (e.pageX - this.offsetLeft - (w / 2)) * (w > h ? (h / w) : 1);
           var y = (e.pageY - this.offsetTop - (h / 2)) * (h > w ? (w / h) : 1);
           var direction = Math.round((((Math.atan2(y, x) * (180 / Math.PI)) + 180) / 90) + 3) % 4; //direction的值为“0,1,2,3”分别对应着“上，右，下，左”
           var eventType = e.type;
           var dirName = new Array('上方','右侧','下方','左侧');
           if(e.type == 'mouseenter'){
              $("#result").html(dirName[direction]+'进入');
          }else{
              $('#result').html(dirName[direction]+'离开');
          }
});