flight

<!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 width = 700,
  		  height = 580;
		var svg = d3.select( "body" )
  		.append( "svg" )
		  .attr( "width", width )
		  .attr( "height", height );
    var projection = d3.geoConicConformal() //quelle projection utiliser ???? Pas forcément important
    									.translate([width/2, height/2])
    									.center([15, 50]).scale(800);
    var path = d3.geoPath() // d3.geo.path avec d3 version 3
                 .projection(projection);
    var path2 = d3.geoPath()
									.projection(projection);
    
	d3.json("custom.geo.json", function(json) {
	    svg.selectAll("path")
           .data(json.features)
           .enter()
           .append("path")
           .attr("d", path)
      		.style("fill",'grey');
		});
    d3.json("map.geojson", function(json) {
	    svg.selectAll("path")
           .data(json.features)
           .enter()
           .append("path")
           .attr("d", path)
      		.style("fill",'grey');
		});
  </script>
</body>

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