Takes a hex color value and spits out a color based on some simple parameters

getClosestColorName.js

const greyThresh = 0.2;
const bwDelta = 20;
const hueMap = {
  0: "red",
  60: "yellow",
  120: "green",
  180: "teal",
  240: "blue",
  300: "purple",
  360: "red"
};

function getClosestColorName(hex) {
  const [r, g, b] = hex
    .slice(1)
    .split(/(.{2})/)
    .filter(_ => _)
    .map(x => parseInt(x, 16));
  let v = Math.max(r, g, b),
    n = v - Math.min(r, g, b);
  let h =
    n && (v == r ? (g - b) / n : v == g ? 2 + (b - r) / n : 4 + (r - g) / n);
  [h, s, v] = [60 * (h < 0 ? h + 6 : h), v && n / v, v];
  return v < 0 + bwDelta
    ? "black"
    : s < greyThresh
    ? v > 255 - bwDelta
      ? "white"
      : "grey"
    : hueMap[
        Object.keys(hueMap).reduce(
          (p, n) => (Math.abs(p) > Math.abs(n - h) ? n - h : p),
          Infinity
        ) + h
      ];
}

console.log(getClosestColorName("#a3fdb2"));