jsPlumb

0. function: jsPlumb provides a means for a developer to visually connect elements on their web pages. It uses SVG and runs on all browsers
   from IE9 and later. 
   
1. clone project from https://github.com/jsplumb/

2. import project to idea

3. run demo
    demo/index.html > right click > open in browser

code: https://github.com/pascal19821003/jsPlumb