Calculating Color Contrast using YIQ

yiq.php

function getContrastYIQ(string $hexColor): string
{
    $hex = str_replace('#', '', $hexColor);

    $r = hexdec(substr($hex, 0, 2));

    $g = hexdec(substr($hex, 2, 2));

    $b = hexdec(substr($hex, 4, 2));

    $yiq = (($r * 299) + ($g * 587) + ($b * 114)) / 1000;

    return ($yiq >= 128) ? '#000000' : '#ffffff';
}

yiq.ts

function getContrastYIQ(hexColor: string): string {
  const hex = hexColor.replace('#', '');

  const r = parseInt(hex.substr(0, 2), 16);

  const g = parseInt(hex.substr(2, 2), 16);

  const b = parseInt(hex.substr(4, 2), 16);

  const yiq = ((r * 299) + (g * 587) + (b * 114)) / 1000;

  return (yiq >= 128) ? '#000000' : '#ffffff';
}