Overlapping Sankey links

<!DOCTYPE html>
<html>
<meta charset="utf-8">
<title>Sankey Diagram</title>
<style>

@import url(https://bost.ocks.org/mike/style.css?20120521);

#chart {
  height: 500px;
}

.node rect {
  cursor: move;
  fill-opacity: .9;
  shape-rendering: crispEdges;
}

.node text {
  pointer-events: none;
  text-shadow: 0 1px 0 #fff;
}

.link {
  fill: none;
  stroke: #000;
  stroke-opacity: .2;
}

.link:hover {
  stroke-opacity: .5;
}

</style>
<body>

<h1><a href="https://bost.ocks.org/mike/sankey/">Original</a></h1>
<p id="chart1">
<h1>Overlapping Links at Targets</h1>
<p id="chart2">
<h1>Overlapping Links at Sources</h1>
<p id="chart3">
<h1>Overlapping at Sources and Targets</h1>
<p id="chart4">

var margin = {top: 1, right: 1, bottom: 6, left: 1},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var formatNumber = d3.format(",.0f"),
    format = function(d) { return formatNumber(d) + " TWh"; },
    color = d3.scale.category20();

function addSankey(overlapSources,overlapTargets,parent) {
  var svg = d3.select("#"+parent).append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
    .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var sankey = d3.sankey()
      .nodeWidth(15)
      .nodePadding(10)
      .size([width, height])
      .overlapLinksAtSources(overlapSources)
      .overlapLinksAtTargets(overlapTargets);

var path = sankey.link();

d3.json("energy.json", function(energy) {

sankey
        .nodes(energy.nodes)
        .links(energy.links)
        .layout(32);

var link = svg.append("g").selectAll(".link")
        .data(energy.links)
      .enter().append("path")
        .attr("class", "link")
        .attr("d", path)
        .style("stroke-width", function(d) { return Math.max(1, d.dy); })
        .sort(function(a, b) { return b.dy - a.dy; });

link.append("title")
        .text(function(d) { return d.source.name + " → " + d.target.name + "\n" + format(d.value); });

node.append("rect")
        .attr("height", function(d) { return d.dy; })
        .attr("width", sankey.nodeWidth())
        .style("fill", function(d) { return d.color = color(d.name.replace(/ .*/, "")); })
        .style("stroke", function(d) { return d3.rgb(d.color).darker(2); })
      .append("title")
        .text(function(d) { return d.name + "\n" + format(d.value); });

node.append("text")
        .attr("x", -6)
        .attr("y", function(d) { return d.dy / 2; })
        .attr("dy", ".35em")
        .attr("text-anchor", "end")
        .attr("transform", null)
        .text(function(d) { return d.name; })
      .filter(function(d) { return d.x < width / 2; })
        .attr("x", 6 + sankey.nodeWidth())
        .attr("text-anchor", "start");

function dragmove(d) {
      d3.select(this).attr("transform", "translate(" + d.x + "," + (d.y = Math.max(0, Math.min(height - d.dy, d3.event.y))) + ")");
      sankey.relayout();
      link.attr("d", path);
    }
  });
}
  
addSankey(false,false,"chart1");
addSankey(false,true,"chart2");
addSankey(true,false,"chart3");
addSankey(true,true,"chart4");

</script>
</html>

Modified http://d3js.org/d3.v2.js to a secure url

https://d3js.org/d3.v2.js