piechart.js

const percent = 0.12;

const startX = getCoordinatesForPercent(0)[0]
const startY = getCoordinatesForPercent(0)[1]
const endX = getCoordinatesForPercent(percent)[0]
const endY = getCoordinatesForPercent(percent)[1]
const largeArcFlag = percent > .5 ? 1 : 0

const pathData = [
  `M ${startX} ${startY}`,
  `A 1 1 0 ${largeArcFlag} 1 ${endX} ${endY}`,
  `L 0 0`,
].join(' ');