D3v4 Map with Zoom

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.js"></script>
  <script src="https://d3js.org/topojson.v2.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    svg { width:100%; height: 100% }
  </style>
</head>

<body>
  <script>
    var width = 900;
    var height = 500;
    
    var svg = d3.select("body").append("svg")
    .call(d3.zoom().on("zoom", function () {
              svg.attr("transform", d3.event.transform)
      }))
      .append("g");
    
    var projection = d3.geoMercator();
    
    var path = d3.geoPath().projection(projection);
      
    var url = "https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/world-50m.json";
    
d3.json(url, function(error, world) {
  if (error) throw error;

svg.selectAll("path")
       .data(topojson.feature(world, world.objects.countries).features)
       .enter().append("path")
       .attr("d", path);
  
});
    
  </script>
</body>

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

https://d3js.org/topojson.v2.min.js