1 var data; // loaded asynchronously

     2 

     3 var path = d3.geo.path();

     4 

     5 var svg = d3.select("#chart")

     6   .append("svg:svg");

     7 

     8 var counties = svg.append("svg:g")

     9     .attr("id", "counties")

    10     .attr("class", "Blues");

    11 

    12 var states = svg.append("svg:g")

    13     .attr("id", "states");

    14 

    15 d3.json("../data/us-counties.json", function(json) {

    16   counties.selectAll("path")

    17       .data(json.features)

    18     .enter().append("svg:path")

    19       .attr("class", data ? quantize : null)

    20       .attr("d", path);

    21 });

    22 

    23 d3.json("../data/us-states.json", function(json) {

    24   states.selectAll("path")

    25       .data(json.features)

    26     .enter().append("svg:path")

    27       .attr("d", path);

    28 });

    29 

    30 d3.json("unemployment.json", function(json) {

    31   data = json;

    32   counties.selectAll("path")

    33       .attr("class", quantize);

    34 });

    35 

    36 function quantize(d) {

    37   return "q" + Math.min(8, ~~(data[d.id] * 9 / 12)) + "-9";

    38 }