model弹出框居中

Modal.prototype.adjustDialog = function () {
    var modalIsOverflowing = this.$element[0].scrollHeight > document.documentElement.clientHeight

    this.$element.css({
      paddingLeft:  !this.bodyIsOverflowing && modalIsOverflowing ? this.scrollbarWidth : ‘‘,
      paddingRight: this.bodyIsOverflowing && !modalIsOverflowing ? this.scrollbarWidth : ‘‘
    })
    // 弹出框居中
    var $modal_dialog = $(this.$element[0]).find(‘.modal-dialog‘);
    var m_top = ( $(window).height() - $modal_dialog.height() )/2;
    $modal_dialog.css({‘margin‘: m_top + ‘px auto‘});
  }