Vector slippy map of rivers built entirely in D3, no other mapping library.

Quickie D3-only slippy map of rivers.

Completely cargo-cult hacked from mbostock's OSM vector tile demo

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  margin: 0;
}

.map {
  position: relative;
  overflow: hidden;
}

.layer {
  position: absolute;
}

.tile {
  position: absolute;
  width: 256px;
  height: 256px;
}

.tile path {
  fill: none;
  stroke: #29439c;
  stroke-linejoin: round; stroke-linecap: round;
}

.info {
  position: absolute;
  bottom: 10px;
  left: 10px;
}

</style>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script src="https://d3js.org/d3.geo.tile.v0.min.js"></script>
<script>

var width = Math.max(960, window.innerWidth),
    height = Math.max(500, window.innerHeight),
    prefix = prefixMatch(["webkit", "ms", "Moz", "O"]),
    order = {rail: 0, minor_road: 1, major_road: 2, highway: 3};

var tile = d3.geo.tile()
    .size([width, height]);

var projection = d3.geo.mercator()
    .scale((1 << 21) / 2 / Math.PI)
    .translate([-width / 2, -height / 2]); // just temporary

var tileProjection = d3.geo.mercator();

var tilePath = d3.geo.path()
    .projection(tileProjection);

var zoom = d3.behavior.zoom()
    .scale(projection.scale() * 2 * Math.PI)
    .scaleExtent([1 << 12, 1 << 23])
    .translate(projection([-121.036, 38.096]).map(function(x) { return -x; }))
    .on("zoom", zoomed);

var map = d3.select("body").append("div")
    .attr("class", "map")
    .style("width", width + "px")
    .style("height", height + "px")
    .call(zoom)
    .on("mousemove", mousemoved);

var layer = map.append("div")
    .attr("class", "layer");

var info = map.append("div")
    .attr("class", "info");

zoomed();

function zoomed() {
  var tiles = tile
      .scale(zoom.scale())
      .translate(zoom.translate())
      ();

projection
      .scale(zoom.scale() / 2 / Math.PI)
      .translate(zoom.translate());

var image = layer
      .style(prefix + "transform", matrix3d(tiles.scale, tiles.translate))
    .selectAll(".tile")
      .data(tiles, function(d) { return d; });

image.exit()
      .each(function(d) { this._xhr.abort(); })
      .remove();

image.enter().append("svg")
      .attr("class", "tile")
      .style("left", function(d) { return d[0] * 256 + "px"; })
      .style("top", function(d) { return d[1] * 256 + "px"; })
      .each(function(d) {
        var svg = d3.select(this);
        this._xhr = d3.json("https://somebits.com:8000/rivers/" + d[2] + "/" + d[0] + "/" + d[1] + ".json", function(error, json) {
          var k = Math.pow(2, d[2]) * 256; // size of the world in pixels

tilePath.projection()
              .translate([k / 2 - d[0] * 256, k / 2 - d[1] * 256]) // [0°,0°] in pixels
              .scale(k / 2 / Math.PI);

svg.selectAll("path")
              .data(json.features)
            .enter().append("path")
              .attr("style", function(d) { return "stroke-width: " + d.properties.strahler/2 + "px;" })
              .attr("d", function(d) { return tilePath(d); });
        });
      });
}

function mousemoved() {
  info.text(formatLocation(projection.invert(d3.mouse(this)), zoom.scale()));
}

function matrix3d(scale, translate) {
  var k = scale / 256, r = scale % 1 ? Number : Math.round;
  return "matrix3d(" + [k, 0, 0, 0, 0, k, 0, 0, 0, 0, k, 0, r(translate[0] * scale), r(translate[1] * scale), 0, 1 ] + ")";
}

function prefixMatch(p) {
  var i = -1, n = p.length, s = document.body.style;
  while (++i < n) if (p[i] + "Transform" in s) return "-" + p[i].toLowerCase() + "-";
  return "";
}

function formatLocation(p, k) {
  var format = d3.format("." + Math.floor(Math.log(k) / 2 - 2) + "f");
  return (p[1] < 0 ? format(-p[1]) + "°S" : format(p[1]) + "°N") + " "
       + (p[0] < 0 ? format(-p[0]) + "°W" : format(p[0]) + "°E");
}

</script>

Modified http://d3js.org/d3.v3.min.js to a secure url

Modified http://d3js.org/d3.geo.tile.v0.min.js to a secure url

https://d3js.org/d3.v3.min.js

https://d3js.org/d3.geo.tile.v0.min.js