V4 simple network graph

Network graph with node labels

<!DOCTYPE html>
<meta charset="utf-8">
<style>
    body {font-family: 'Architects Daughter', cursive;}
</style>
<svg width="960" height="600"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<link href="https://fonts.googleapis.com/css?family=Architects+Daughter" rel="stylesheet">
<script>

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }))
    .force("charge", d3.forceManyBody().strength(-400))
    .force("center", d3.forceCenter(width / 2, height / 2));

d3.json("data.json", function(error, graph) {
  if (error) throw error;
  
  graph.links.forEach(function(d){
    d.source = d.source_id;    
    d.target = d.target_id;
  });

var link = svg.append("g")
                .style("stroke", "#aaa")
                .selectAll("line")
                .data(graph.links)
                .enter().append("line");

var node = svg.append("g")
            .attr("class", "nodes")
  .selectAll("circle")
            .data(graph.nodes)
  .enter().append("circle")
          .attr("r", 6)
          .call(d3.drag()
              .on("start", dragstarted)
              .on("drag", dragged)
              .on("end", dragended));
  
  var label = svg.append("g")
      .attr("class", "labels")
      .selectAll("text")
      .data(graph.nodes)
      .enter().append("text")
        .attr("class", "label")
        .text(function(d) { return d.name; });

simulation
      .nodes(graph.nodes)
      .on("tick", ticked);

simulation.force("link")
      .links(graph.links);

node
         .attr("r", 20)
         .style("fill", "#d9d9d9")
         .style("stroke", "#969696")
         .style("stroke-width", "1px")
         .attr("cx", function (d) { return d.x+6; })
         .attr("cy", function(d) { return d.y-6; });
    
    label
    		.attr("x", function(d) { return d.x; })
            .attr("y", function (d) { return d.y; })
            .style("font-size", "20px").style("fill", "#4393c3");
  }
});

function dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart()
  simulation.fix(d);
}

function dragged(d) {
  simulation.fix(d, d3.event.x, d3.event.y);
}

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  simulation.unfix(d);
}

</script>

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