Force Layout with fixed Mouseover Labels

<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/d3@2.1.3/d3.js"></script>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/d3@2.1.3/d3.geom.js"></script>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/d3@2.1.3/d3.layout.js"></script>
    <style type="text/css">

.link {
  stroke: #ccc;
}

.node:not(:hover) .nodetext {
  display: none;
}

</style>
  </head>
  <body>
    <script type="text/javascript">

var w = 960,
    h = 500

var vis = d3.select("body").append("svg:svg")
    .attr("width", w)
    .attr("height", h);

d3.json("readme.json", function(err, json) {
    var force = d3.layout.force()
        .nodes(json.nodes)
        .links(json.links)
        .gravity(.05)
        .distance(100)
        .charge(-100)
        .size([w, h])
        .start();

var link = vis.selectAll("line.link")
        .data(json.links)
      .enter().append("svg:line")
        .attr("class", "link");

var node = vis.selectAll("g.node")
        .data(json.nodes)
      .enter().append("svg:g")
        .attr("class", "node")
        .call(force.drag);

var image = node.append("svg:image")
        .attr("xlink:href", "https://d3nwyuy0nl342s.cloudfront.net/images/icons/public.png")
        .attr("x", "-8px")
        .attr("y", "-8px")
        .attr("width", "16px")
        .attr("height", "16px");

node.append("svg:text")
        .attr("class", "nodetext")
        .attr("dx", ".35em")
        .attr("dy", "1em")
        .text(function(d) { return d.name });

force.on("tick", function() {
      link.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; });

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

</script>
  </body>
</html>

Modified http://mbostock.github.com/d3/d3.js?2.1.3 to a secure url

Modified http://mbostock.github.com/d3/d3.geom.js?2.1.3 to a secure url

Modified http://mbostock.github.com/d3/d3.layout.js?2.1.3 to a secure url

https://mbostock.github.com/d3/d3.js?2.1.3

https://mbostock.github.com/d3/d3.geom.js?2.1.3

https://mbostock.github.com/d3/d3.layout.js?2.1.3