bootstrap 3.3 模态框垂直居中问题

/* center modal */
function centerModals(){
$('.modal').each(function(i){
var $clone = $(this).clone().css('display', 'block').appendTo('body');    var top = Math.round(($clone.height() - $clone.find('.modal-content').height()) / 2);
top = top > 0 ? top : 0;
$clone.remove();
$(this).find('.modal-content').css("margin-top", top);
});
}
$('.modal').on('show.bs.modal', centerModals);
$(window).on('resize', centerModals);