Static Force Layout + dragging

This demonstrates how to produce a static force-directed graph layout with d3-force. Rather than updating the graph with each tick, we run the graph a fixed number of times, and then display it once. To avoid freezing the user interface, it may be desirable to compute the force-directed layout in a web worker.

<!DOCTYPE html>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height"),
    g = svg.append("g").attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");

var n = 100,
    nodes = d3.range(n).map(function(i) { return {index: i}; }),
    links = d3.range(n).map(function(i) { return {source: i, target: (i + 3) % n}; });

var simulation = d3.forceSimulation(nodes)
    .force("charge", d3.forceManyBody().strength(-80))
    .force("link", d3.forceLink(links).distance(20).strength(1).iterations(10))
    .force("x", d3.forceX())
    .force("y", d3.forceY())
    .stop();

var loading = svg.append("text")
    .attr("dy", "0.35em")
    .attr("text-anchor", "middle")
    .attr("font-family", "sans-serif")
    .attr("font-size", 10)
    .text("Simulating. One moment please…");

var dragstarted = function(d) {
  if (!d3.event.active) {
    simulation.alpha(.5);
    simulation.alphaTarget(0.1).restart();
  }
  d.fx = d.x;
  d.fy = d.y;
}

var dragged = function (d) {
  d.fx = d3.event.x;
  d.fy = d3.event.y;
}

var dragended = function(d) {
  if (!d3.event.active) simulation.alphaTarget(0.0001);
  d.fx = null;
  d.fy = null;
}

// Use a timeout to allow the rest of the page to load first.
d3.timeout(function() {
  loading.remove();

// See https://github.com/d3/d3-force/blob/master/README.md#simulation_tick
  for (var i = 0, n = Math.ceil(Math.log(simulation.alphaMin()) / Math.log(1 - simulation.alphaDecay())); i < n; ++i) {
    simulation.tick();
  }

g.append("g")
      .attr("stroke", "#000")
      .attr("stroke-width", 1.5)
    .selectAll("line")
    .data(links)
    .enter().append("line")
      .attr("x1", function(d) { return d.source.x; })
      .attr("y1", function(d) { return d.source.y; })
      .attr("x2", function(d) { return d.target.x; })
      .attr("y2", function(d) { return d.target.y; });

g.append("g")
      .attr("stroke", "#fff")
      .attr("stroke-width", 1.5)
    .selectAll("circle")
    .data(nodes)
    .enter().append("circle")
      .attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; })
      .attr("r", 4.5)
      .call(d3.drag()
        .on("start", dragstarted)
        .on("drag", dragged)
        .on("end", dragended)
      );
  
  simulation.on("tick", ticked);
});

</script>

https://d3js.org/d3.v4.min.js