react-diagrams/demos/demo-labelled-links/index.tsx

import {
	DiagramEngine,
	DiagramModel,
	DefaultNodeModel,
	LinkModel,
	DefaultPortModel,
	DiagramWidget,
	DefaultLinkModel
} from "storm-react-diagrams";
import * as React from "react";
import { DemoWorkspaceWidget } from "../.helpers/DemoWorkspaceWidget";
import { action } from "@storybook/addon-actions";

export default () => {
	// setup the diagram engine
	const engine = new DiagramEngine();
	engine.installDefaults();

	// setup the diagram model
	const model = new DiagramModel();

	// create four nodes
	const node1 = new DefaultNodeModel("Node A", "rgb(0,192,255)");
	const port1 = node1.addOutPort("Out");
	node1.setPosition(100, 100);

	const node2 = new DefaultNodeModel("Node B", "rgb(255,255,0)");
	const port2 = node2.addInPort("In");
	node2.setPosition(400, 50);

	const node3 = new DefaultNodeModel("Node C (no label)", "rgb(192,255,255)");
	const port3 = node3.addInPort("In");
	node3.setPosition(450, 180);

	const node4 = new DefaultNodeModel("Node D", "rgb(192,0,255)");
	const port4 = node4.addInPort("In");
	node4.setPosition(300, 250);

	// link node A and B together and give it a label
	const link1 = port1.link(port2);
	(link1 as DefaultLinkModel).addLabel("Custom label 1");
	(link1 as DefaultLinkModel).addLabel("Custom label 2");

	// no label for A and C, just a link
	const link2 = port1.link(port3);

	// also a label for A and D
	const link3 = port1.link(port4);
	link3.setTargetPort(port4);
	(link3 as DefaultLinkModel).addLabel("Emoji label: 🎉");

	// add all to the main model
	model.addAll(node1, node2, node3, node4, link1, link2, link3);

	// load model into engine and render
	engine.setModel(model);

	return (
		<DemoWorkspaceWidget
			buttons={
				<button
					onClick={() => {
						action("Serialized Graph")(JSON.stringify(model.serializeDiagram(), null, 2));
					}}
				>
					Serialize Graph
				</button>
			}
		>
			<DiagramWidget className="srd-demo-canvas" diagramEngine={engine} />
		</DemoWorkspaceWidget>
	);
};