diff --git a/d3js.js b/d3js.js
new file mode 100644
index 0000000..6b87ac8
--- /dev/null
+++ b/d3js.js
@@ -0,0 +1,136 @@
+      var m = [20, 120, 20, 120],
+      w = 1280 - m[1] - m[3],
+      h = 800 - m[0] - m[2],
+      i = 0,
+      root;
+
+      var tree = d3.layout.tree()
+      .size([h, w]);
+
+      var diagonal = d3.svg.diagonal()
+      .projection(function(d) { return [d.y, d.x]; });
+
+      var vis = d3.select("#body").append("svg:svg")
+      .attr("width", w + m[1] + m[3])
+      .attr("height", h + m[0] + m[2])
+      .append("svg:g")
+      .attr("transform", "translate(" + m[3] + "," + m[0] + ")");
+
+      d3.json("madrid-destino.json", function(json) {
+      root = json;
+      root.x0 = h / 2;
+      root.y0 = 0;
+
+      function toggleAll(d) {
+      if (d.children) {
+      d.children.forEach(toggleAll);
+      toggle(d);
+      }
+      }
+
+      // Initialize the display to show a few nodes.
+      root.children.forEach(toggleAll);
+
+      update(root);
+      });
+
+      function update(source) {
+      var duration = d3.event && d3.event.altKey ? 5000 : 500;
+
+      // Compute the new tree layout.
+      var nodes = tree.nodes(root).reverse();
+
+      // Normalize for fixed-depth.
+      nodes.forEach(function(d) { d.y = d.depth * 180; });
+
+      // Update the nodes…
+      var node = vis.selectAll("g.node")
+      .data(nodes, function(d) { return d.id || (d.id = ++i); });
+
+      // Enter any new nodes at the parent's previous position.
+      var nodeEnter = node.enter().append("svg:g")
+      .attr("class", "node")
+      .attr("transform", function(d) { return "translate(" + source.y0 + "," + source.x0 + ")"; })
+      .on("click", function(d) { toggle(d); update(d); });
+
+      nodeEnter.append("svg:circle")
+      .attr("r", 1e-6)
+      .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });
+
+      nodeEnter.append("svg:text")
+      .attr("x", function(d) { return d.children || d._children ? -10 : 10; })
+      .attr("dy", ".35em")
+      .attr("text-anchor", function(d) { return d.children || d._children ? "end" : "start"; })
+      .text(function(d) { return d.name; })
+      .style("fill-opacity", 1e-6);
+
+      // Transition nodes to their new position.
+      var nodeUpdate = node.transition()
+      .duration(duration)
+      .attr("transform", function(d) { return "translate(" + d.y + "," + d.x + ")"; });
+
+      nodeUpdate.select("circle")
+      .attr("r", 4.5)
+      .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });
+
+      nodeUpdate.select("text")
+      .style("fill-opacity", 1);
+
+      // Transition exiting nodes to the parent's new position.
+      var nodeExit = node.exit().transition()
+      .duration(duration)
+      .attr("transform", function(d) { return "translate(" + source.y + "," + source.x + ")"; })
+      .remove();
+
+      nodeExit.select("circle")
+      .attr("r", 1e-6);
+
+      nodeExit.select("text")
+      .style("fill-opacity", 1e-6);
+
+      // Update the links…
+      var link = vis.selectAll("path.link")
+      .data(tree.links(nodes), function(d) { return d.target.id; });
+
+      // Enter any new links at the parent's previous position.
+      link.enter().insert("svg:path", "g")
+      .attr("class", "link")
+      .attr("d", function(d) {
+      var o = {x: source.x0, y: source.y0};
+      return diagonal({source: o, target: o});
+      })
+      .transition()
+      .duration(duration)
+      .attr("d", diagonal);
+
+      // Transition links to their new position.
+      link.transition()
+      .duration(duration)
+      .attr("d", diagonal);
+
+      // Transition exiting nodes to the parent's new position.
+      link.exit().transition()
+      .duration(duration)
+      .attr("d", function(d) {
+      var o = {x: source.x, y: source.y};
+      return diagonal({source: o, target: o});
+      })
+      .remove();
+
+      // Stash the old positions for transition.
+      nodes.forEach(function(d) {
+      d.x0 = d.x;
+      d.y0 = d.y;
+      });
+      }
+
+      // Toggle children.
+      function toggle(d) {
+      if (d.children) {
+      d._children = d.children;
+      d.children = null;
+      } else {
+      d.children = d._children;
+      d._children = null;
+      }
+      }
diff --git a/index.html b/index.html
index e1acff2..89cbde9 100644
--- a/index.html
+++ b/index.html
@@ -5,6 +5,7 @@
     <title>Estructura de Madrid-Destino 2016</title>
     <link type="text/css" rel="stylesheet" href="style.css"/>
     <script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
+    <script src="d3js.js" charset="utf-8"></script>
     <style type="text/css">
       .node circle {
       cursor: pointer;
@@ -33,142 +34,6 @@
       </div>
     </div>
     <script type="text/javascript">
-      var m = [20, 120, 20, 120],
-      w = 1280 - m[1] - m[3],
-      h = 800 - m[0] - m[2],
-      i = 0,
-      root;
-
-      var tree = d3.layout.tree()
-      .size([h, w]);
-
-      var diagonal = d3.svg.diagonal()
-      .projection(function(d) { return [d.y, d.x]; });
-
-      var vis = d3.select("#body").append("svg:svg")
-      .attr("width", w + m[1] + m[3])
-      .attr("height", h + m[0] + m[2])
-      .append("svg:g")
-      .attr("transform", "translate(" + m[3] + "," + m[0] + ")");
-
-      d3.json("madrid-destino.json", function(json) {
-      root = json;
-      root.x0 = h / 2;
-      root.y0 = 0;
-
-      function toggleAll(d) {
-      if (d.children) {
-      d.children.forEach(toggleAll);
-      toggle(d);
-      }
-      }
-
-      // Initialize the display to show a few nodes.
-      root.children.forEach(toggleAll);
-
-      update(root);
-      });
-
-      function update(source) {
-      var duration = d3.event && d3.event.altKey ? 5000 : 500;
-
-      // Compute the new tree layout.
-      var nodes = tree.nodes(root).reverse();
-
-      // Normalize for fixed-depth.
-      nodes.forEach(function(d) { d.y = d.depth * 180; });
-
-      // Update the nodes…
-      var node = vis.selectAll("g.node")
-      .data(nodes, function(d) { return d.id || (d.id = ++i); });
-
-      // Enter any new nodes at the parent's previous position.
-      var nodeEnter = node.enter().append("svg:g")
-      .attr("class", "node")
-      .attr("transform", function(d) { return "translate(" + source.y0 + "," + source.x0 + ")"; })
-      .on("click", function(d) { toggle(d); update(d); });
-
-      nodeEnter.append("svg:circle")
-      .attr("r", 1e-6)
-      .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });
-
-      nodeEnter.append("svg:text")
-      .attr("x", function(d) { return d.children || d._children ? -10 : 10; })
-      .attr("dy", ".35em")
-      .attr("text-anchor", function(d) { return d.children || d._children ? "end" : "start"; })
-      .text(function(d) { return d.name; })
-      .style("fill-opacity", 1e-6);
-
-      // Transition nodes to their new position.
-      var nodeUpdate = node.transition()
-      .duration(duration)
-      .attr("transform", function(d) { return "translate(" + d.y + "," + d.x + ")"; });
-
-      nodeUpdate.select("circle")
-      .attr("r", 4.5)
-      .style("fill", function(d) { return d._children ? "lightsteelblue" : "#fff"; });
-
-      nodeUpdate.select("text")
-      .style("fill-opacity", 1);
-
-      // Transition exiting nodes to the parent's new position.
-      var nodeExit = node.exit().transition()
-      .duration(duration)
-      .attr("transform", function(d) { return "translate(" + source.y + "," + source.x + ")"; })
-      .remove();
-
-      nodeExit.select("circle")
-      .attr("r", 1e-6);
-
-      nodeExit.select("text")
-      .style("fill-opacity", 1e-6);
-
-      // Update the links…
-      var link = vis.selectAll("path.link")
-      .data(tree.links(nodes), function(d) { return d.target.id; });
-
-      // Enter any new links at the parent's previous position.
-      link.enter().insert("svg:path", "g")
-      .attr("class", "link")
-      .attr("d", function(d) {
-      var o = {x: source.x0, y: source.y0};
-      return diagonal({source: o, target: o});
-      })
-      .transition()
-      .duration(duration)
-      .attr("d", diagonal);
-
-      // Transition links to their new position.
-      link.transition()
-      .duration(duration)
-      .attr("d", diagonal);
-
-      // Transition exiting nodes to the parent's new position.
-      link.exit().transition()
-      .duration(duration)
-      .attr("d", function(d) {
-      var o = {x: source.x, y: source.y};
-      return diagonal({source: o, target: o});
-      })
-      .remove();
-
-      // Stash the old positions for transition.
-      nodes.forEach(function(d) {
-      d.x0 = d.x;
-      d.y0 = d.y;
-      });
-      }
-
-      // Toggle children.
-      function toggle(d) {
-      if (d.children) {
-      d._children = d.children;
-      d.children = null;
-      } else {
-      d.children = d._children;
-      d._children = null;
-      }
-      }
     </script>
   </body>
 </html>