function isColor(col) {

  const cache = isColor[col]

  if (cache != null) {

    console.log('- reading cache')

    return cache

  }

  isColor.el.style = ''

  isColor.el.style.color = col

  return isColor[col] = !!isColor.el.style.color

}

isColor.el = document.createElement('div')

console.log('is "red" a color?', isColor('red'))

console.log('from the cache: ', isColor('red'))

console.log('is "rgbx(1, 2, 3)" a color?', isColor('rgbx(1, 2, 3)'))

console.log('is "#0f0" a color?', isColor('#0f0'))

console.log('is "hsl(192, 50%, 50%)" a color?', isColor('hsl(192, 50%, 50%)'))

console.log('from the cache: ', isColor('hsl(192, 50%, 50%)'))

console.log('is "lab(2000.1337% -8.6911 -159.131231 / .987189732)" ?',

  isColor('lab(2000.1337% -8.6911 -159.131231 / .987189732)'))

console.log('is "snippetZone" ?', isColor('snippetZone'))