How can I get the D3.js axis ticks and positions as an array?

Question

I usually place my axis ticks on the svg using this:

d3.svg.axis().scale(xScale(width)).ticks(4)

Is it possible to get these tick values a

Answer 1

Yes, xScale.ticks(4) should give you the actual tick points as values, and you can pipe those back through your xScale to the the X position. You can also just pull the tick points back from the generated elements after you apply the axis to an actual element:

var svg = d3.select("svg");

var scale = d3.scale.linear()
    .range([20, 280])
    .domain([0, 100])

var axis = d3.svg.axis().scale(scale).orient("bottom").ticks(9);
// grab the "scale" used by the axis, call .ticks()
// passing the value we have for .ticks()
console.log("all the points", axis.scale().ticks(axis.ticks()[0]));
// note, we actually select 11 points not 9, "closest guess"

// paint the axis and then find its ticks
svg.call(axis).selectAll(".tick").each(function(data) {
  var tick = d3.select(this);
  // pull the transform data out of the tick
  var transform = d3.transform(tick.attr("transform")).translate;

  // passed in "data" is the value of the tick, transform[0] holds the X value
  console.log("each tick", data, transform);
});

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