Contrast YIQ

function getContrastYIQ(hexcolor){
  const r = parseInt(hexcolor.substr(0,2), 16)
  const g = parseInt(hexcolor.substr(2,2), 16)
  const b = parseInt(hexcolor.substr(4,2), 16)
  const yiq = ((r * 299) + (g * 587) + (b * 114)) / 1000
  return (yiq >= 128) ? 'black' : 'white'
}