$.fn.boxCenter = function() {
return this.each(function(i){
var w = $(this).width();
var h = $(this).height();
var mtop = (h/2)*(-1);
var mleft = (w/2)*(-1);
$(this).css({"width": + w + "px" ,"height": + h + "px" , "top": "50%" , "left": "50%" , "margin-top": + mtop + "px" , "margin-left": + mleft+ "px"});
});
};