D3.js: Generate the ticks for an axis without having to render them to the svg. Allows us to adapt the tickSize and tickPadding to these values before drawing rather than afterwards.

d3.axis.ticks.js

/**
 * Generate the tick values for a given axis
 * Reference: https://github.com/mbostock/d3/blob/master/src/svg/axis.js
 */
function getAxisTicks(axis) {
  var scale1 = axis.scale(),
      tickArguments_ = axis.ticks(),
      tickValues = axis.tickValues(),
      ticks;
      
  ticks = tickValues == null ? (scale1.ticks ? scale1.ticks.apply(scale1, tickArguments_) : scale1.domain()) : tickValues,

  return ticks;
}