nice.js

function d3_scale_nice(domain, nice) {
  var i0 = 0,
      i1 = domain.length - 1,
      x0 = domain[i0],
      x1 = domain[i1],
      dx;

  if (x1 < x0) {
    dx = i0; i0 = i1; i1 = dx;
    dx = x0; x0 = x1; x1 = dx;
  }

  if (dx = x1 - x0) {
    nice = nice(dx);
    domain[i0] = nice.floor(x0);
    domain[i1] = nice.ceil(x1);
  }

  return domain;
}

function d3_scale_niceDefault() {
  return Math;
}