converter hex to rgb / rgb to hex

colorConverter.ts

type Color = { r: number, g: number, b: number };
function hexToRgb(hex: string): Color {
    if (hex.length === 3) {
        let [hr, hg, hb] = hex.split(''); // ['F', '0', '0']
        return hexToRgb(`${hr}${hr}${hg}${hg}${hb}${hb}`);
    }
    let [r, g, b] = [0, 2, 4]
        .map(offset => hex.substring(offset, offset + 2)) // ['FF', '00', '00']
        .map(hex => parseInt(hex, 16)); // [255, 0, 0]

    return {r, g, b};
}

function rgbToHex(r: number, g: number, b: number): string {
    return [r, g, b]
        .map(dec => dec.toString(16)) // ['ff', '0', '0']
        .map(hex => hex.length === 1 ? `0${hex}` : hex) // ['ff', '00', '00']
        .join('');
}

console.log(hexToRgb('00f'));
console.log(rgbToHex(255, 0, 0));