Simple logic to convert RGB color-space to HSL

HexToHSL.js

class color {
  static getLightness(R, G, B) {
    const r = R / 255,
      g = G / 255,
      b = B / 255;

    const max = Math.max(r, g, b);
    const min = Math.min(r, g, b);

    return (max + min) / 2;
  }
  static getSaturation(R, G, B, l) {
    if (R === G && G === B) return 0;

    const r = R / 255,
      g = G / 255,
      b = B / 255;

    const max = Math.max(r, g, b);
    const min = Math.min(r, g, b);

    if (l <= 0.5) return (max - min) / (max + min);
    else if (l > 0.5) return (max - min) / (2 - max - min);
  }
  static getHue(R, G, B) {
    if (R === G && G === B) return 0;

    const r = R / 255,
      g = G / 255,
      b = B / 255;

    const max = Math.max(r, g, b);
    const min = Math.min(r, g, b);

    let hue;

    if (max === r) hue = (g - b) / (max - min);
    else if (max === g) hue = 2 + (b - r) / (max - min);
    else if (max === b) hue = 4 + (r - g) / (max - min);

    return hue * 60;
  }
    static hexTohsl(str) {
    let rgb = hexToDecimal(str);
    let l = color.getLightness(...rgb);
    let s = color.getSaturation(...rgb, l);
    let h = color.getHue(...rgb);

    if (h < 0) h += 360;

    return {
      h,
      s: (s * 100),
      l: (l * 100),
    };
  }
  static rgbTohsl(...rgb) {
    let l = color.getLightness(...rgb);
    let s = color.getSaturation(...rgb, l);
    let h = color.getHue(...rgb);
    if (h < 0) h += 360;
    return { h, s: s*100, l: l*100 };
  }
}
function getHexArray(str) {
  let hex = str.trim().toLowerCase().replace(/^#/, "");
  hex = hex.length === 3 ? `${hex}${hex}` : hex;
  const result = hex.match(/(\d|[a-f]){2}/g);
  if (!result || result.length !== 3) throw new Error("Invalid Hex String");
  return result;
}
function hexToDecimal(ary) {
  let hex = ary;
  if (!Array.isArray(ary)) hex = getHexArray(hex);
  return hex.map((c) => parseInt(c, 16));
}