for placing text on interval rect bars, is there an easy option to align text center to center of the bar? e.g. offset to half width of the interval rect bar?

[tx0c]

I'm doing a month graph with rect with { x, interval }, want to place text on top of each bar at center, if I don't specify textAnchor then text is placed center aligning the left side of the bar, not desired; then I use textAnchor: "start", but can only align start of text to left of the bar;
this monthly rect bar is similar to Plot.barX chart but difference is each month bar is a little bit different width, e.g. most February has 28 days vs other months' 30 or 31 days width, so February is always a bit narrower, hard to align it with just dx hard-coded offset;

    Plot.rectY(tagsAllPerMonth, {
      x: "month", interval: d3.utcMonth, y: "count",
      stroke: "black", rx: 8, }),
    Plot.text(tagsAllPerMonth, {
      x: "month", interval: d3.utcMonth, y: "count",
      text: "count", dy: -6, textAnchor: "start",
    }),

I think the correct dx should be a function like dx: d => (x(NextMonth) - x(CurrentMonth)) / 2, but still have not figured out a correct expression, where can I get a reference of the domain mapping function x ?

    Plot.text(tagsAllPerMonth, {
      x: "month", interval: d3.utcMonth, y: "count",
      text: "count", dy: -6, // textAnchor: "start", // leave textAnchor default to "center"
      dx:    d => (xNextMonth - xCurrentMonth) / 2,
    }),

[Fil]

Plot.textY doesn't have the interval transform (#597), but you might want to do one of:

add 14 days:

x: d => +d3.utcMonth.floor(d["date_of_birth"]) + 14 * 24 * 3600 * 1000

compute the middle of the month:

x: d => (+d3.utcMonth.floor(d["date_of_birth"]) + +d3.utcMonth.ceil(1 + +d["date_of_birth"])) / 2

see https://observablehq.com/@fil/plot-center-text-on-an-interval