Javascript 为什么$（'；#cy'；）.cytoscape可以工作？

我有以下代码正在使用和。在下面的代码中，

$（'#cy'）.cytoscape

是什么意思？我不理解第一部分（即，选择id为cy的元素），但它似乎调用了名为cytoscape的函数，并将一个对象作为其参数传递。jQuery为什么理解这里的cytoscape方法

var init=function () { 
  $('#cy').cytoscape({
     elements: [n1,n2,n3,n4,e1,e2],
     layout: {name: 'preset'},
     style: [style1,style2]
  });
}

$(init);

---

这里是完整的代码，只是为了完整；在相应的html页面中有一个id为“cy”的

标记：

var n1={ // node n1
      data: { // element data (put dev data here)
        id: 'n1', // mandatory for each element, assigned automatically on undefined
        parent: 'nparent', // indicates the compound node parent id; not defined => no parent
      },
      scratch: {
        foo: 'bar'
      },
      position: { // the model position of the node (optional on init, mandatory after)
        x: 100,
        y: 100
      },
      selected: false, // whether the element is selected (default false)
      selectable: true, // whether the selection state is mutable (default true)
      locked: false, // when locked a node's position is immutable (default false)
      grabbable: true, // whether the node can be grabbed and moved by the user
      classes: 'foo bar' // a space separated list of class names that the element has
    };

var n2={ // node n2
      data: { id: 'n2' },
      renderedPosition: { x: 200, y: 200 } // can alternatively specify position in rendered on-screen pixels
    };

var n3={ // node n3
      data: { id: 'n3', parent: 'nparent' },
      position: { x: 123, y: 234 }
    };

var n4=
    { // node nparent
      data: { id: 'nparent', position: { x: 200, y: 100 } }
    };

var e1={ // edge e1
      data: {
        id: 'e1',
        // inferred as an edge because `source` and `target` are specified:
        source: 'n1', // the source node id (edge comes from this node)
        target: 'n2'  // the target node id (edge goes to this node)
      }
    };
var e2={ // edge e1
      data: {
        id: 'e2',
        // inferred as an edge because `source` and `target` are specified:
        source: 'nparent', // the source node id (edge comes from this node)
        target: 'n2'  // the target node id (edge goes to this node)
      }
    };
var style1={
      selector: 'node',
      style: {
        'content': 'data(id)'
      }
    };

var style2={
      selector: ':parent',
      style: {
        'background-opacity': 0.8
      }
    };

var init=function () { 
  $('#cy').css("background-color", "pink");
  $('#cy').cytoscape({
     elements: [n1,n2,n3,n4,e1,e2],
     layout: {name: 'preset'},
     style: [style1,style2]
  });
}

$(init);

---

到目前为止，它没有文档记录/不推荐使用，因为它使得获取Cytoscape实例对象更加困难，还有其他原因。它在3.0中不受支持