通过获取鼠标的点击位置来动态定位元素

$(document).on('click','.caina_span',function(e){    var block=$('.zan').css('display');    if($.trim(block)=='block'){        return false;    }   var positionY=e.pageY;   var positionX=e.pageX;    $('.zan').css({"top":+(positionY-50)+"px","left":+(positionX-100)+"px","display":"block"});    $('.caina_span').removeClass('clicked');    $(this).hide();})