Yes, JointJS supports NodeJS environment. Note that only models are supported (element, link, graph). For example, you can build your graph on the server side, then stringify it to JSON, send it to the client and there you can display that graph:
Install jointjs: npm install jointjs
Create your graph in NodeJS:
var joint = require('jointjs');
var graph = new joint.dia.Graph;
var el1 = new joint.shapes.basic.Rect({ position: { x: 50, y: 50 }, attrs: { text: { fill: 'yellow' } }});
var el2 = new joint.shapes.basic.Rect({ position: { x: 300, y: 200 }, attrs: { text: { fill: 'yellow' } }});
var link = new joint.dia.Link({ source: { id: el1.id }, target: { id: el2.id } });
graph.addCells([el1, el2, link]);
Do what you need with the graph:
storeToDBOrSendToClient(graph.toJSON())
As long as you work with JointJS models, you can take advantage of all the features of JointJS in NodeJS environment.