Clipped Conic Conformal by mbostock

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>
<script>

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

var graticule = d3.geoGraticule().extentMajor([[-135, 0], [135, 90]]),
    outline = graticule.outline(),
    projection = d3.geoConicConformal().fitSize([width, height], outline),
    path = d3.geoPath().projection(projection);

var defs = svg.append("defs");

defs.append("path")
    .attr("id", "extent")
    .attr("d", path(outline));

defs.append("clipPath")
    .attr("id", "clip")
  .append("use")
    .attr("xlink:href", "#extent");

var g = svg.append("g")
    .attr("clip-path", "url(#clip)");

g.append("path")
    .attr("id", "graticule")
    .attr("fill", "none")
    .attr("stroke", "#777")
    .attr("stroke-width", 0.5)
    .attr("stroke-opacity", 0.5)
    .attr("d", path(graticule()));

g.append("use")
    .attr("fill", "none")
    .attr("stroke", "#000")
    .attr("xlink:href", "#extent");

d3.json("https://d3js.org/world-50m.v1.json", function(error, world) {
  if (error) throw error;

  g.insert("path", "#graticule")
      .attr("fill", "#222")
      .attr("d", path(topojson.feature(world, world.objects.land)));

  g.insert("path", "#graticule")
      .attr("fill", "none")
      .attr("stroke", "#fff")
      .attr("stroke-width", 0.5)
      .attr("d", path(topojson.mesh(world, world.objects.countries, function(a, b) { return a !== b; })));
});

</script>