Gene mapping 2.0

<!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>

<body>
  <script>
    var svg = d3.select("body").append("svg")
      .attr("width", 960)
      .attr("height", 500)
    
     svg.append("text")
      .text("Gene Mapping")
      .attr("y", 72)
      .attr("x", 304)
      .style("font-size", 36)
      .style("font-family", "monospace")
  
    d3.json("data.json", function(err, mydata) {
    var g = d3.select("svg").selectAll("rect")
    .data(mydata)
    .enter()
    .append("g")
    .attr("transform", function (d){
          if (d.orientation == 'forward') {
            return "translate(" + -(d.stop-d.start) + ",100)";
          }
          else {
            return "translate(" + d.start + ",125)";
          }
          })
    ;
     
    g.transition()
     .duration(1000)
     .delay(function (d) {return d.start})
     .attr("transform", function (d){
          if (d.orientation == 'forward') {
            return "translate(" + d.start +",100)";
          }
          else {
            return "translate(" + 960 + ",125)";
          }
          })
    
    g.append("rect")
    .attr("height",50)
    
    .attr("width",function (d) {
      return d.stop-d.start;
    })
    
    .attr("fill", function (d) {
     if (d.orientation == "forward"){return "green";
     }
     else if (d.oreientation == "reverse"){
       return "red";
     }
   })
    .attr("stroke-width", 3)
    .attr("stroke","#000000")
    g.append("text")
    .attr("x", function (d) {return (d.stop-d.start)/2})
    .attr("y", 25)
    .text(function (d) {return d.name; })
    .attr("text-anchor", "middle")
    .attr("alignment-baseline", "central"); 
    })
  </script>
</body>

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