sector.js

// source: https://github.com/marianc000/pieChart
// from https://stackoverflow.com/questions/5736398/how-to-calculate-the-svg-path-for-an-arc-of-a-circle

export function getD(radius, startAngle, endAngle) {
  const isCircle = endAngle - startAngle === 360;
  if (isCircle) {
    endAngle--;
  }
  const start = polarToCartesian(radius, startAngle);
  const end = polarToCartesian(radius, endAngle);

  const largeArcFlag = endAngle - startAngle <= 180 ? 0 : 1;
  const d = [
    "M", start.x, start.y,
    "A", radius, radius, 0, largeArcFlag, 1, end.x, end.y];

  if (isCircle) {
    d.push("Z");
  } else {
    d.push("L", radius, radius,
      "L", start.x, start.y,
      "Z");
  }

  return d.join(" ");
}

function round(n) {
  return Math.round(n * 10) / 10;
}

function polarToCartesian(radius, angleInDegrees) {
  var radians = (angleInDegrees - 90) * Math.PI / 180;

  return {
    x: round(radius + (radius * Math.cos(radians))),
    y: round(radius + (radius * Math.sin(radians)))
  };
}