Result
jQuery
jQuery.fn.center = function () {
//position:absolute;を与えて、ウィンドウのサイズを取得し、topとleftの値を調整
this.css("position","absolute");
this.css("top", ( $(window).height() - this.height() ) / 2+$(window).scrollTop() + "px");
this.css("left", ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + "px");
return this;
};
$("div").center();css
div{
width:100px;
height:100px;
background:#eee;
}