arrows.html

<svg id="network" width="600" height="380">
  <defs>
    <marker
      id="triangle"
      viewBox="0 0 10 10"
      refX="20"
      refY="5"
      markerUnits="strokeWidth"
      markerWidth="8"
      markerHeight="8"
      orient="auto"
    >
      <path d="M 0 0 L 10 5 L 0 10 z" fill="rgba(0,0,0,0.2)" />
    </marker>
  </defs>
</svg>

<script type="module">
  import { network } from "https://cdn.jsdelivr.net/npm/@gramex/network@2";
  import * as d3 from "https://cdn.jsdelivr.net/npm/d3@7/+esm";

  // Load the data
  const data = await fetch("flare.json").then((r) => r.json());
  var root = d3.hierarchy(data);

  // Create the network
  const graph = network("#network", {
    links: root.links(),
    nodes: root.descendants(),
    d3,
  });

  // Style the network
  const color = d3.scaleOrdinal(d3.schemeCategory10);
  graph.nodes.attr("fill", (d) => color(d.depth)).attr("r", (d) => 10 - d.depth * 2);
  graph.links.attr("stroke", "rgba(0,0,0,0.2)").attr("marker-end", "url(#triangle)");
</script>