Color as hexadecimal string to RGBA array

hex2RGBA.ts

function hex2RGBA(hex: string) {
  if(hex !== null && hex.charAt(0) === '#') {
    const pattern = /[0-9a-f]{1,2}/ig,
        rgba = [0, 0, 0, 255];
    for(
        let i = 0, match;
        i < 4 && (match = pattern.exec(hex)) !== null;
        i++
    )
        rgba[i] = parseInt(match.toString(), 16);
    return rgba;
  }else
    return [0, 0, 0, 0];
}