homewrok 7 url

<!DOCTYPE html>
<meta charset="utf-8">
<style>
  
path.counties, path.county-border {
  fill: none;
  stroke: #000;
  stroke-opacity: .2;
}
path.state {
  fill: none;
  stroke: #000;
}
path.quake, circle.quake {
  fill: crimson;
  fill-opacity: 0.4;
}
</style>
<svg width="960" height="960"></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/d3-tile.v0.0.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
var data = null;
var smallest = 2.5;
var pi = Math.PI,
    tau = 2 * pi;
var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");
var projection = d3.geoMercator()
    .scale((1 << 15) / tau)
    .translate([width / 2, height / 2])
    .center([-98.5355, 32.965]);
var path = d3.geoPath()
    .projection(projection);
  
var ok = "https://raw.githubusercontent.com/deldersveld/topojson/master/countries/us-states/OK-40-oklahoma-counties.json";

d3.json(ok, function(error, ok) {
  if (error) throw error;
  var tiles = d3.tile()
      .size([width, height])
      .scale(projection.scale() * tau)
      .translate(projection([0, 0]))
      ();
  svg.selectAll("image")
      .data(tiles)
    .enter().append("image")
      .attr("xlink:href", function(d) { return "https://" + "abc"[d[1] % 3] + ".tile.openstreetmap.org/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })
      .attr("x", function(d) { return (d[0] + tiles.translate[0]) * tiles.scale; })
      .attr("y", function(d) { return (d[1] + tiles.translate[1]) * tiles.scale; })
      .attr("width", tiles.scale)
      .attr("height", tiles.scale);
});
var base = "https://gist.githubusercontent.com/pbogden/935370a5272acff2618b/raw/f4d102d819066bb21a0021b4cbab6502e86bf587/";
var usgs = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson";
var url = base + "quakes.json";
d3.json(url, plotQuakes);
d3.json(base + "ok.json", plotState);
function plotQuakes(error, json) {
  if (error) console.log(error);
  data = json;
  var features = data.features.filter(function(d) { return (+ d.properties.mag >= smallest) });
  
  var layer2 = svg.append("g");
  layer2.selectAll("path.quake")
      .data(features)
    .enter().append("path")
      .attr("class", "quake")
      .attr("d", path)
}
function plotState(error, ok) {
  if (error) console.log(error);

var objects = ok.objects.ok;
 var all = topojson.merge(ok, objects.geometries);
 var layer1 = svg.append("g");

layer1.append("path")
      .datum(all)
      .attr("class", "state")
      .attr("d", path);
  
layer1.append("path")
      .datum(topojson.mesh(ok, objects, function(a, b) { return a !== b; }))
      .attr("class", "county-border")
      .attr("d", path);
}
</script>

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

https://d3js.org/d3-tile.v0.0.min.js

https://d3js.org/topojson.v1.min.js