Genome Map Names?

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

var svg = d3.select("body").append("svg")
      .attr("width", 960)
      .attr("height", 500)

d3.json("data.json", function(err, mydata) {
      d3.select("svg").selectAll("rect")
        .data(mydata)
      	.enter()      
      	.append("svg:g")
      	.attr("y", function (d) {
        	if (d.orientation == "forward") {
            return 100;}
        	else if (d.orientation == "reverse") {
            return 125;}})         
      	.attr("height", 50)      
      	.attr("stroke", "#7c7c7c")      
      	.attr("x", function (d) 
          {return d.start;})     
      	.attr("width", function (d) 
          {return d.stop - d.start;})      
      	.attr("fill", function(d) 
          {if (d.orientation == "forward") 
          {return "#7c7c7c";}  
        	else if (d.orientation == "reverse") 
          {return "#ebca83";}		});		})
    
  </script>
</body>

https://d3js.org/d3.v4.min.js