jquery ui中的ui.draggable是什么意思

Question

var $photo = $("#photo");

var $trash = $("#trash");

$("li").draggable({

  revert: "invalid",

  helper: "clone",

  cursor: "move"

});

$trash.droppable({

  accept: "#photo li",

  activeClass: "highlight",

  drop: function(event, ui){

    abc(ui.draggable);      //ui是什么东西，ui.draggable又是什么意思

  }

});

Answer 1

如下图所示：