example-d3-map.js

d3.json('data.geojson').then(function(bb) {
  let width = 200, height = 200;
  let projection = d3.geoEqualEarth();
  projection.fitSize([width, height], bb);
  let geoGenerator = d3.geoPath()
  .projection(projection);

  let svg = d3.select("body").append('svg')
  .style("width", width).style("height", height);

  svg.append('g').selectAll('path')
  .data(bb.features)
  .join('path')
  .attr('d', geoGenerator)
  .attr('fill', '#088')
  .attr('stroke', '#000');
});