Simplifying and cleaning Shapefiles.

quantize.js

us.coordinates = us.coordinates.map(function(polygon) {
  return polygon.map(function(lineString) {
    return lineString.map(function(point) {
      return point.map(function(coordinate) {
        return d3.round(coordinate, 2);
      });
    });
  })
});

d3.select("body").text(JSON.stringify(us));