forceLayoutTooltip.js

let JSONFILENAME = "collaborationNetwork.json"

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height"),
    radius = 30;

var color = d3.scaleOrdinal(d3.schemeCategory10);

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }))
    .force("charge", d3.forceManyBody().distanceMin(20).distanceMax(150).strength(-20))
    .force("center", d3.forceCenter(width / 2, height / 2));

// Define the div for the tooltip
    var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

d3.json(JSONFILENAME, function(error, graph) {
  if (error) throw error;

  var link = svg.append("g")
    .attr("class", "links")
    .selectAll("line")
    .data(graph.links)
    .enter().append("line")
      .attr("stroke-width", 4);

  var node = svg.append("g")
    .attr("class", "nodes")
    .selectAll("circle")
    .data(graph.nodes)
    .enter().append("circle")
    .attr("r", 10)
    .attr("fill", function(d) { return color(d.group); })
    .on("mouseover", function(d) {
            div.transition()
                .duration(100)
                .style("opacity", .9);
            div	.html(d.name)
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
            })
    .on("mouseout", function(d) {
                    div.transition()
                        .duration(1000)
                        .style("opacity", .0);
                    })
    .call(d3.drag()
    .on("start", dragstarted)
    .on("drag", dragged)
    .on("end", dragended))
    .on("dblclick", dblclick)
    ;


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

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

// adding github logo with link
      var imgs = svg.selectAll("image").data([0]);
           imgs.enter()
          .append("svg:image")
          .attr("xlink:href", "./images/GitHub-Mark-120px-plus.png")
          .attr("x", 0)
          .attr("y", height-40)
          .attr("width", "40")
          .attr("height", "40")
          .on("click", githubclick)


  function ticked() {


    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; });

    node
        .attr("cx", function(d) { return d.x; })
        .attr("cy", function(d) { return d.y; });

    node.attr("cx", function(d) { return d.x = Math.max(radius, Math.min(width - radius, d.x)); })
        .attr("cy", function(d) { return d.y = Math.max(radius, Math.min(height - radius, d.y)); });

  }
});

function dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d.fx = d.x;
  d.fy = d.y;
}

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

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  d.fx = null;
  d.fy = null;
}


 function dblclick(a){
   window.location.assign(a.url, '_blank');
}

 function githubclick(a){
     window.location.assign("https://github.com/floklimm/collaborationNetworkIllustration", '_blank');
  }