network

<!DOCTYPE html>
<meta charset="utf-8">
 <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
 <script src="https://marvl.infotech.monash.edu/webcola/cola.v3.min.js"></script>

<style>

.node circle {
  fill: #DDD;
  stroke: #777;
  stroke-width: 2px;
}

.node text {
  font-family: sans-serif;
  text-anchor: middle;
  pointer-events: none;
  user-select: none;
  -webkit-user-select: none;
}

.link {
  stroke: #88A;
  stroke-width: 4px;  
  marker-end: url(#end-arrow);
}

text {
  font: 18px sans-serif;
  pointer-events: none;
}

#end-arrow {
  fill: #88A;
}
  
  
</style>
<body>

var links = [
  {source: "A", target: "D", type: "high"},
  {source: "A", target: "K", type: "high"},
  {source: "B", target: "G", type: "high"},
  {source: "C", target: "A", type: "low"},
  {source: "D", target: "K", type: "low"},
  {source: "E", target: "A", type: "low"},
  {source: "F", target: "B", type: "low"},
  {source: "K", target: "J", type: "low"},
  {source: "F", target: "A", type: "low"},
  {source: "F", target: "I", type: "low"},
  {source: "G", target: "H", type: "low"},
  {source: "E", target: "K", type: "high"},
  {source: "E", target: "G", type: "low"},
  {source: "E", target: "F", type: "high"},
  {source: "D", target: "E", type: "high"}  
];

var nodes = {};

// Compute the distinct nodes from the links.
links.forEach(function(link) {
  link.source = nodes[link.source] || (nodes[link.source] = {name: link.source});
  link.target = nodes[link.target] || (nodes[link.target] = {name: link.target});
});

var width = 960,
    height = 700;

var force = d3.layout.force()
    .nodes(d3.values(nodes))
    .links(links)
    .size([width, height])
    .linkDistance(105)
    .charge(-775)
    .on("tick", tick)
    .start();

force.on("start", function () {
    console.log("start");
});
force.on("end", function () {
    console.log("end");
});

R=18
  
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

// add defs-marker
svg.append('svg:defs')
    .append('svg:marker')
    .attr('id', 'end-arrow')
    .attr('viewBox', '0 0 10 10')
    .attr('refX', 2+R)
    .attr('refY', 5)
     .attr('markerWidth', 4)
     .attr('markerHeight', 4)
    .attr('orient', 'auto')
    .append('svg:path')
    .attr('d', 'M0,0 L0,10 L10,5 z');

var link = svg.selectAll(".link")
    .data(force.links())
    .enter()
    .append("line")
    .attr("class", "link")
    .attr('marker-end', 'url(#end-arrow)')
;

var node = svg.selectAll(".node")
    .data(force.nodes())
    .enter().append("g")
    .attr("class", "node")
    .on("mouseover", mouseover)
    .on("mouseout", mouseout)
    .call(force.drag);

node.append("circle")
    .attr("r", R);

node.append("text")
    .attr("x", 0)
    .attr("dy", ".35em")
    .text(function(d) { return d.name; });

node
      .attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; });
}

function mouseover() {
  d3.select(this).select("circle").transition()
      .duration(750)
      .attr("r", R+8);
  
   d3.select(this).select("text").transition()
      .duration(750)
      .style("font-size", '32px')
      .attr("dy", ".3em")
   ;
}

function mouseout() {
  d3.select(this).select("circle").transition()
      .duration(750)
      .attr("r", R);
  
   d3.select(this).select("text").transition()
      .duration(750)
      .style("font-size", '18px')
      .attr("dy", ".35em");
}

</script>

Modified http://marvl.infotech.monash.edu/webcola/cola.v3.min.js to a secure url

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js

https://marvl.infotech.monash.edu/webcola/cola.v3.min.js