Q:

Adding text to links that is represented in a JSON list - D3.js tree layout

I have the following code , and i'm trying to append text to my links (i need to represent country names on top of the link), notice that the text is embedded within a json list, and that's why i think i cant get it into my links:
<! DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">

    <title>Collapsible Tree Example</title>

    <style>
    .node circle {
      fill: #fff;
      stroke: steelblue;
      stroke-width: 3px;
    }
    .node text { font: 12px sans-serif; }
    .link {
      fill: none;
      stroke: #ccc;
      stroke-width: 2px;
    }

    </style>

  </head>

  <body>

<!--  load the d3.js library --> 
<script src="http://d3js.org/d3.v3.min.js"></script>

<script>
var treeData = [
  {"name":["1"],"weights":["17284"],"variableNames":["Country name"],"criteria":
  {"levels":["","Brazil","Canada","France","Germany","Spain","Turkey","United Kingdom","United States"]},
  "children":[{"name":["2"],"weights":["5920"],"variableNames":["Country name"],
  "criteria":{"levels":["","Brazil","Canada","France","Germany","Spain","Turkey","United Kingdom","United States"]},
  "children":[{"name":["3 "],"weights":["604"],"prediction":["0.256"]},{"name":["4 "],"weights":["5316"],"prediction":["0.231"]}],"prediction":["0.233"]},{"name":["5"],"weights":["11364"],
  "variableNames":["Country name"],"criteria":{"levels":["","Brazil","Canada","France","Germany","Spain","Turkey","United Kingdom","United States"]},
  "children":[{"name":["6 "],"weights":["10029"],"prediction":["0.153"]},{"name":["7 "],"weights":["1335"],
  "prediction":["0.053"]}],"prediction":["0.141"]}],"prediction":["0.173"]} 
];
// ************** Generate the tree diagram  *****************
var margin = {top: 20, right: 120, bottom: 20, left: 120},
    width = 960 - margin.right - margin.left,
    height = 500 - margin.top - margin.bottom;

var i = 0;
var tree = d3.layout.tree()
    .size([height, width]);
var diagonal = d3.svg.diagonal()
    .projection(function(d) { return [d.y, d.x]; });
var svg = d3.select("body").append("svg")
    .attr("width", width + margin.right + margin.left)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
root = treeData[0];

update(root);
function update(source) {
  // Compute the new tree layout. 
  var nodes = tree.nodes(root).reverse(),
      links = tree.links(nodes);
  // Normalize for fixed-depth. 
  nodes.forEach(function(d) { d.y = d.depth * 180; });
  // Declare the nodes…
  var node = svg.selectAll("g.node")
      .data(nodes, function(d) { return d.id || (d.id = ++i); });
  // Enter the nodes. 
  var nodeEnter = node.enter().append("g")
      .attr("class", "node")
      .attr("transform", function(d) { 
          return "translate(" + d.y + "," + d.x + ")"; });
  nodeEnter.append("circle")
      .attr("r", 10)
      .style("fill", "#fff");

  nodeEnter.append("text")
      .attr("x", function(d) { 
          return d.children || d._children ?  -13 : 13; })
      .attr("dy", ".35em")
      .attr("text-anchor", function(d) { 
          return d.children || d._children ? " end" : "start"; })
      .text(function(d) { return d.name; })
      .style("fill-opacity", 1);

  // Declare the links…
  var link = svg.selectAll("path.link")
      .data(links, function(d) { return d.target.id; });
  // Enter the links. 
  link.enter().insert("path", "g")
      .attr("class", "link")
      .attr("d", diagonal);

link.append("text")
      .attr("x", function(d) { 
          return d.children || d._children ?  -13 : 13; })
      .attr("dy", ".35em")
      .attr("text-anchor", function(d) { 
          return d.children || d._children ? " end" : "start"; })
      .text(function(d) { return d.source.criteria.levels; }) // also tried d.source.criteria
      .style("fill-opacity", 1);
}
</script>

  </body>
</html>

I tried to get help from other questions like this one: Adding text labels to force directed graph links in d3.js
But couldn't find any question that had an embedded list. 
Thanks in Advance!! 

A:

The key is that you define the links setup just like the nodes, i.e. build a g that contains the path and the text.  In your example, the text ends up in the path elements, respectively. 
So this is key:
var linkG = link.enter()
  .append('g')
  .attr('class', 'link');

Here's a fiddle
(I changed a few bit here and there as well... not that I wasn't sure what texts you want to display)

