Support link.id.

[mbostock]

Like from d3-force, link.id. It would allow you to specify an accessor function that computes a unique string identifier for a given node; that function would then be applied to each input node, then joined with the source and target of each input link to compute the graph.

For example, if you said:

sankey.nodeId(d => d.name);

You could then give as input:

{
  "nodes": [
    {"name": "A"},
    {"name": "B"},
    {"name": "C"}
  ],
  "links": [
    {"source": "A", "target": "B", "value": 1},
    {"source": "A", "target": "C", "value": 2},
    {"source": "B", "target": "C", "value": 3}
  ]
}