text: 
  // -------------------------------------------------
  
    var graphs = [];
  
    $.getJSON( "graphs.json", function( data ) {
      graphs = data.graphs;
      console.log(graphs);
  
      for (i in graphs){
        $("#dataFile").append('<option value="' + i + '">' + graphs[i].name + '</li>'); 
      }
  
      $("#dataFile").val(6);
  
      //console.log(document.getElementById("dataFile").value);
  
  
  
      loadData(6);
  
    });
  
  
  
    function loadData(graph = 0) {
  
      // console.log("in loadData");
      // console.log(graphs[graph].file);
  
      var units = "Datasets";
  
      var margin = {top: 10, right: 10, bottom: 10, left: 10},
          width = 1000 - margin.left - margin.right,
          height = 1000 - margin.top - margin.bottom;
  
      var formatNumber = d3.format(",.0f"),    // zero decimal places
          format = function(d) { return formatNumber(d) + " " + units; },
          color = d3.scale.category20();
  
      // append the svg canvas to the page
      var svg = d3.select("#chart").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 + ")");
  
      // Set the sankey diagram properties
      var sankey = d3.sankey()
          .nodeWidth(36)
          .nodePadding(12)
          .size([width, height]);
  
      var path = sankey.link();
  
  //    var fileName = "distributions.csv";
      var fileName = graphs[graph].file;
  
      svg.selectAll('*').remove();  //  clear existig graph
  
      var dataFile = "csv/" + fileName;
      if (!dataFile) {
        alert("please select a data file!");
      }
      
      document.getElementById("chartTitle").innerHTML = dataFile;
  
      d3.csv(dataFile, function(error, data) {
  
        //set up graph in same style as original example but empty
        graph = {"nodes" : [], "links" : []};
  
          data.forEach(function (d) {
            graph.nodes.push({ "name": d.source });
            graph.nodes.push({ "name": d.target });
            graph.links.push({ "source": d.source,
                               "target": d.target,
                               "value": +d.value });
           });
  
           // return only the distinct / unique nodes
           graph.nodes = d3.keys(d3.nest()
             .key(function (d) { return d.name; })
             .map(graph.nodes));
  
           // loop through each link replacing the text with its index from node
           graph.links.forEach(function (d, i) {
             graph.links[i].source = graph.nodes.indexOf(graph.links[i].source);
             graph.links[i].target = graph.nodes.indexOf(graph.links[i].target);
           });
  
           //now loop through each nodes to make nodes an array of objects
           graph.nodes.forEach(function (d, i) {
             graph.nodes[i] = { "name": d };
           });
  
        sankey
          .nodes(graph.nodes)
          .links(graph.links)
          .layout(32);
      
        var link = svg.append("g").selectAll(".link") // add in the links
            .data(graph.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")  // add the link titles
              .text(function(d) {
              return d.source.name + " → " + 
                      d.target.name + "\n" + format(d.value); });
  
        var node = svg.append("g").selectAll(".node") // add nodes
            .data(graph.nodes)
          .enter().append("g")
            .attr("class", "node")
            .attr("transform", function(d) { 
            return "translate(" + d.x + "," + d.y + ")"; })
          .call(d3.behavior.drag()
            .origin(function(d) { return d; })
            .on("dragstart", function() { 
            this.parentNode.appendChild(this); })
            .on("drag", dragmove));
  
        node.append("rect") // add the rectangles for nodes
            .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")  // add node titles
            .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) {  // function for moving nodes
          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);
        }
      });
  
    }
  