Horizontal Bar Chart

<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<head>
<script src="https://d3js.org/d3.v3.min.js"></script>
  <style type="text/css">
    rect {
        fill:teal;
        fill-opacity:.8;
    }
  </style>
</head>
<body>
  <script type="text/javascript">
 
    var margin = {top: 50, bottom: 10, left:300, right: 40};
    var width = 900 - margin.left - margin.right;
    var height = 900 - margin.top - margin.bottom;
 
    var xScale = d3.scale.linear().range([0, width]);
    var yScale = d3.scale.ordinal().rangeRoundBands([0, height], .8, 0);
 
    var svg = d3.select("body").append("svg")
                .attr("width", width+margin.left+margin.right)
                .attr("height", height+margin.top+margin.bottom);
 
    var g = svg.append("g")
                .attr("transform", "translate("+margin.left+","+margin.top+")");
 
    d3.json("countries_2012.json", function(data) {
 
        var max = d3.max(data, function(d) { return d.population; } );
        var min = 0;

xScale.domain([min, max]);
        yScale.domain(data.map(function(d) { return d.name; }));
 
        var groups = g.append("g")
                    .selectAll("text")
                    .data(data)
                  .enter()
                    .append("g");
 
        var bars = groups
                    .append("rect")
                    .attr("width", function(d) { return xScale(d.population); })
                    .attr("height", 5)
                    .attr("x", xScale(min))
                    .attr("y", function(d) { return yScale(d.name); })
    });
  </script>
</body>
</html>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js