get proper font color for background

gistfile1.txt

function getAccessibleColor(rgb) {
  let [ r, g, b ] = rgb;

  let colors = [r / 255, g / 255, b / 255];

  let c = colors.map((col) => {
    if (col <= 0.03928) {
      return col / 12.92;
    }
    return Math.pow((col + 0.055) / 1.055, 2.4);
  });

  let L = (0.2126 * c[0]) + (0.7152 * c[1]) + (0.0722 * c[2]);

  return (L > 0.179)
    ? [ 0, 0, 0 ]
    : [ 255, 255, 255 ];
}