fold by two (grids)

<!DOCTYPE html>
<meta charset="utf-8">
<style>
body {
  font-family: Helvetica;
  font-size: 10px;
}

rect {
  fill: none;
  stroke: black;
  stroke-width: 1;
}
</style>
<body>
<script src="https://d3js.org/d3.v4.js"></script>
<script src="https://romsson.github.io/d3-gridding/build/d3-gridding.js"></script>
<script>

var width = 600,
    height = 400;

var max_depth = 15;

var gridding = d3.gridding();

var data =  d3.range(2);

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
  .append("g");

function draw(params, data, level = 0) {

gridding.params(params);

var griddingData = gridding(data);

svg.selectAll(".square_" + level)
      .data(griddingData)
    .enter()
      .append("rect")
      .attr("class", ".square_" + level)
      .attr("width", function(d) { return d.width; })
      .attr("height", function(d) { return d.height; })
      .attr("transform", function(d) {
        return "translate(" + d.x + "," + d.y + ")";
      });

// A0, A1, A2, ..
  //svg.selectAll(".index_" + level)
  //    .data(griddingData)
  //  .enter().append("text")
  //    .attr("class", "index_" + level)
  //    .style('text-anchor', 'middle')
  //    .style('dominant-baseline', 'central')
  //    .attr("transform", function(d) {
  //      return "translate(" + d.cx + "," + d.cy + ")";
  //    })
  //    .text(function(d, i) {
  //      if(i === 1 && level < 9)
  //        return "A" + level;
  //    });

var d = griddingData[0];

if(level < max_depth) {

draw({
      size: [d.width, d.height],
      offset: [d.x, d.y],
      mode: level % 2 === 0 ? "horizontal": "vertical"
    }, data, level + 1);

}

draw({
  size: [width, height],
  offset: [0, 0],
  mode: "vertical"
}, data);

</script>

Modified http://d3js.org/d3.v4.js to a secure url

Modified http://romsson.github.io/d3-gridding/build/d3-gridding.js to a secure url

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

https://romsson.github.io/d3-gridding/build/d3-gridding.js