How can I generate the opposite color according to current color?

Question

I\'m trying to create a color opposite of current color. I mean if current color is black, then I need to generate white.

Actually I have a text

Answer 1

Simple and elegant.

function invertHex(hex) {
  return (Number(`0x1${hex}`) ^ 0xFFFFFF).toString(16).substr(1).toUpperCase()
}

invertHex('00FF00'); // Returns FF00FF