Invert d3 scaleBand

scale.js

// https://github.com/d3/d3-scale/blob/11777dac7d4b0b3e229d658aee3257ea67bd5ffa/src/band.js#L32
x.invert = function(_) {
    const scale = this;
    const domain = scale.domain;
    const paddingOuter = scale.paddingOuter();
    const paddingInner = scale.paddingInner();
    const step = scale.step();

    const range = scale.range();
    var domainIndex,
      n = domain().length,
      reverse = range[1] < range[0],
      start = range[reverse - 0],
      stop = range[1 - reverse];

    if (_ < start + paddingOuter * step) domainIndex = 0;
    else if (_ > stop - paddingOuter * step) domainIndex = n - 1;
    else domainIndex = Math.floor((_ - start - paddingOuter * step) / step);

    return domain()[domainIndex];
  };