diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/examples/choropleth/choropleth.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/examples/choropleth/choropleth.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,38 @@
+var data; // loaded asynchronously
+
+var path = d3.geo.path();
+
+var svg = d3.select("#chart")
+  .append("svg:svg");
+
+var counties = svg.append("svg:g")
+    .attr("id", "counties")
+    .attr("class", "Blues");
+
+var states = svg.append("svg:g")
+    .attr("id", "states");
+
+d3.json("../data/us-counties.json", function(json) {
+  counties.selectAll("path")
+      .data(json.features)
+    .enter().append("svg:path")
+      .attr("class", data ? quantize : null)
+      .attr("d", path);
+});
+
+d3.json("../data/us-states.json", function(json) {
+  states.selectAll("path")
+      .data(json.features)
+    .enter().append("svg:path")
+      .attr("d", path);
+});
+
+d3.json("unemployment.json", function(json) {
+  data = json;
+  counties.selectAll("path")
+      .attr("class", quantize);
+});
+
+function quantize(d) {
+  return "q" + Math.min(8, ~~(data[d.id] * 9 / 12)) + "-9";
+}