color.js

//From https://github.com/mattdesl/kelvin-to-rgb/blob/master/index.js
function kelvinToRGB (temp) {
  
  let out = [0, 0, 0];

  temp = temp / 100

  let red, blue, green

  if (temp <= 66) {
    red = 255
  } else {
    red = temp - 60
    red = 329.698727466 * Math.pow(red, -0.1332047592)
    if (red < 0) {
      red = 0
    }
    if (red > 255) {
      red = 255
    }
  }

  if (temp <= 66) {
    green = temp
    green = 99.4708025861 * Math.log(green) - 161.1195681661
    if (green < 0) {
      green = 0
    }
    if (green > 255) {
      green = 255
    }
  } else {
    green = temp - 60
    green = 288.1221695283 * Math.pow(green, -0.0755148492)
    if (green < 0) {
      green = 0
    }
    if (green > 255) {
      green = 255
    }
  }

  if (temp >= 66) {
    blue = 255
  } else {
    if (temp <= 19) {
      blue = 0
    } else {
      blue = temp - 10
      blue = 138.5177312231 * Math.log(blue) - 305.0447927307
      if (blue < 0) {
        blue = 0
      }
      if (blue > 255) {
        blue = 255
      }
    }
  }

  out[0] = Math.floor(red)
  out[1] = Math.floor(green)
  out[2] = Math.floor(blue)
  return out
}

//From https://stackoverflow.com/questions/2353211/hsl-to-rgb-color-conversion
function rgbToHsl(r, g, b){
    r /= 255, g /= 255, b /= 255;
    let max = Math.max(r, g, b), min = Math.min(r, g, b);
    let h, s, l = (max + min) / 2;

    if(max == min){
        h = s = 0; // achromatic
    }else{
        let d = max - min;
        s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
        switch(max){
            case r: h = (g - b) / d + (g < b ? 6 : 0); break;
            case g: h = (b - r) / d + 2; break;
            case b: h = (r - g) / d + 4; break;
        }
        h /= 6;
    }

    return [h * 360, s * 100, l * 100];
}

hsbk_to_css.js

const colour = {
    "Hue": hue,
    "Saturation":100 * parseFloat(saturation),
    "Brightness":100 * parseFloat(brightness),
    "Kelvin":parseInt(kelvin)
};

if(colour.Saturation == 0) {
    const rgb = kelvinToRGB(targetColor.Kelvin);
    const hsl = rgbToHsl(rgb[0], rgb[1], rgb[2]);
    colour.Hue = hsl[0]
    colour.Saturation = 10 + ((Math.abs(colour.Kelvin - 7000) / 500) * 3)
}

const background_color = `hsl("${colour.Hue},${colour.Saturation}%,${colour.Brightness / 1.666}%")`;