D3 Examples - Religions Bar Chart

Religions Bar Chart
A bar chart showing population of World religions in 2010. Data shown is from the Pew-Templeton Global Religious Futures Project.
This data is taken exactly as-is from the Pew-Templeton Web site, including labels for religions, and does not represent my opinions. This data may not be 100% accurate, I'm not sure. I'd be curious to see results from others sources that show a similar comparison of World religions.
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<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>D3 Example</title>
    <script src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
    <link href='https://fonts.googleapis.com/css?family=Playfair+Display' rel='stylesheet' type='text/css'>
    <script src="//cdnjs.cloudflare.com/ajax/libs/d3-tip/0.6.3/d3-tip.min.js"></script>
    <style>
    
      .axis text {
        font-family: 'Playfair Display', serif;
        font-size: 24pt;
      }
      .axis .label {
        font-size: 40pt;
      }
​
      .axis path, .axis line {
        fill: none;
        stroke: #000;
        shape-rendering: crispEdges;
      }
      .y.axis path, .y.axis line {
        stroke: none;
      }
​
      .tooltip {
        font-family: 'Playfair Display', serif;
        font-size: 24pt;
​
        /* This trick adds a heavy white shadow around the text. */
        text-shadow: 
          0px 0px 6px white,
          0px 0px 6px white,
          0px 0px 6px white,
          0px 0px 6px white,
          0px 0px 6px white,
          0px 0px 6px white,
          0px 0px 6px white,
          0px 0px 6px white,
          0px 0px 6px white;
​
        /* This eliminates the possibility of flickering tooltips. */
        pointer-events: none;
      }
​
    </style>
  </head>
  <body>
    <script>
​
      var outerWidth = 960;
      var outerHeight = 500;
      var margin = { left: 240, top: 0, right: 0, bottom: 101 };
      var barPadding = 0.2;
      var barPaddingOuter = 0.1;
​
      var xColumn = "population";
      var yColumn = "religion";
      var xAxisLabelText = "Population in 2010";
      var xAxisLabelOffset = 80;
​
      var innerWidth  = outerWidth  - margin.left - margin.right;
      var innerHeight = outerHeight - margin.top  - margin.bottom;
​
      var svg = d3.select("body").append("svg")
        .attr("width",  outerWidth)
        .attr("height", outerHeight);
      var g = svg.append("g")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
      var xAxisG = g.append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(0," + innerHeight + ")")
      var xAxisLabel = xAxisG.append("text")
        .style("text-anchor", "middle")
        .attr("x", innerWidth / 2)
        .attr("y", xAxisLabelOffset)
        .attr("class", "label")
        .text(xAxisLabelText);
      var yAxisG = g.append("g")
        .attr("class", "y axis");
​
      var tooltip = svg.append("text").attr("class", "tooltip");
​
      var xScale = d3.scale.linear().range([0, innerWidth]);
      var yScale = d3.scale.ordinal().rangeRoundBands([0, innerHeight], barPadding, barPaddingOuter);
​
      // Use D3's number format that generates SI prefixes for the X axis.
      // See also https://en.wikipedia.org/wiki/Metric_prefix#List_of_SI_prefixes
      var siFormat = d3.format("s");
      function tickFormat(num){
        // Replace the confusing G (for Giga) with 
        // the more recognizable B (for Billion).
        return siFormat(num).replace("G", "B");
      }
​
      var xAxis = d3.svg.axis().scale(xScale).orient("bottom")
        .ticks(5)
        .tickFormat(tickFormat)
        .outerTickSize(0);
      var yAxis = d3.svg.axis().scale(yScale).orient("left")
        .outerTickSize(0);
​
      var tooltipFormat = d3.format(",");
      function showTooltip(d){
        tooltip.text(tooltipFormat(d[xColumn]) + " people")
          .attr("x", d3.event.pageX + 20)       
          .attr("y", d3.event.pageY);   
      }
      function hideTooltip(){
        tooltip.text("");
      }
​
      function render(data){
​
        xScale.domain([0, d3.max(data, function (d){ return d[xColumn]; })]);
        yScale.domain(       data.map( function (d){ return d[yColumn]; }));
​
        xAxisG.call(xAxis);
        yAxisG.call(yAxis);
​
        var bars = g.selectAll("rect").data(data);
        bars.enter().append("rect")
          .attr("height", yScale.rangeBand())
          .on("mouseover", showTooltip)
          .on("mousemove", showTooltip)
          .on("mouseout", hideTooltip);
        bars
          .attr("x", 0)
          .attr("y",     function (d){ return yScale(d[yColumn]); })
          .attr("width", function (d){ return xScale(d[xColumn]); });
        bars.exit().remove();
      }
​
      function type(d){
        d.population = +d.population;
        return d;
      }
​
      d3.csv("religions2010.csv", type, render);
​
    </script>
  </body>
</html>
​
    