ATTRIBUTE_VJS_PORT_ID
constATTRIBUTE_VJS_PORT_ID:"data-vjs-port-id"="data-vjs-port-id"
This attribute indicates the ID of the logical port that the element represents. A logical port is one which exists in the data model, but connections to/from the port in the UI are shown as being attached to the vertex to which the port belongs. Don't confuse this with the data-vjs-port attribute. When you drag a connection to/from some DOM element with this attribute set, you are instructing VisuallyJs to associate the source/target of the new edge with a port with the specified ID, but that the edge should be connected visually to the DOM element representing the vertex.
Dom Attribute
Context
edge-dragging