sort-colors-js/index.js

js lib to sort colors by hue

const constructColor = hexString => {
  const hex = hexString.replace(/#/g, '');
  /* Get the RGB values to calculate the Hue. */
  const r = parseInt(hex.substring(0, 2), 16) / 255;
  const g = parseInt(hex.substring(2, 4), 16) / 255;
  const b = parseInt(hex.substring(4, 6), 16) / 255;

  /* Getting the Max and Min values for Chroma. */
  const max = Math.max.apply(Math, [r, g, b]);
  const min = Math.min.apply(Math, [r, g, b]);

  /* Variables for HSV value of hex color. */
  let chr = max - min;
  let hue = 0;
  let val = max;
  let sat = 0;

  if (val > 0) {
    /* Calculate Saturation only if Value isn't 0. */
    sat = chr / val;
    if (sat > 0) {
      if (r === max) {
        hue = 60 * ((g - min - (b - min)) / chr);
        if (hue < 0) {
          hue += 360;
        }
      } else if (g === max) {
        hue = 120 + 60 * ((b - min - (r - min)) / chr);
      } else if (b === max) {
        hue = 240 + 60 * ((r - min - (g - min)) / chr);
      }
    }
  }
  const colorObj = {};
  colorObj.hue = hue;
  colorObj.hex = hexString;
  return colorObj;
};

export default sortColorsByHue = colors => {
  return colors
    .map(color => constructColor(color))
    .sort((a, b) => {
      return a.hue - b.hue;
    })
    .map(color => color.hex);
};