Bootstrap的modal拖动效果

(function(){
  function moveModal($this){
    var $head = $this.find('.modal-header');
    var $dialog = $this.find('.modal-dialog');
    var move = {
      isMove: false,
      left: 0,
      top: 0
    };
    //委托
    console.log('点击的是',$this);
    $this.on('mousemove', function(e){
      if(!move.isMove) return;
      console.log('移动的是', e.target);
      $dialog.offset({
        top: e.pageY - move.top,
        left: e.pageX - move.left
      });
    }).on('mouseup', function(e){
      move.isMove = false;
    });
    $head.on('mousedown', function(e){
      move.isMove = true;
      var offset = $dialog.offset();
      move.left = e.pageX - offset.left;
      move.top = e.pageY - offset.top;
    });
  }
  var oldModal = $.fn.modal;
  $.fn.modal = function(o, _r){
    var $this = $(this);
    if(!$this.attr('ifbindmv')){
      $this.attr('isbindmv','1');
      moveModal($this);
    }
    return oldModal.call(this, o, _r);
  }
  ////要拖动的div背景
  //$('#showErr').modal({backdrop: 'static'});
})();