Do you want to list ports in your stencil and let the user drag and drop them into the elements? Do you want the user to be able to edit the position of the ports in the element later? Or remove a port with a double click? Check out this demo.
Drag ports to elements, reposition them, or try removing them.
The source code of this demo is available as part of the JointJS+ commercial license. Don't have a license yet? Start a trial and use the source code of this and many other demos for free, with no obligations, for 30 days.