CSS RGB(A) to Hexadecimal

RGBtoHEX.ts

function RGBtoHEX(color: string): string {
    const channels = color
        // Remove white space.
        .trim()
        .replace(/\s/gu, "")
        // Remove "rgb" or "rgba".
        .replace(/rgba?/u, "")
        // Remove brackets.
        .replace("(", "")
        .replace(")", "")
        // Split channels into numbers.
        .split(",")
        .map(number => parseInt(number))

    const [r = 0, g = 0, b = 0] = channels

    // Pad left hex numbers. E.g "0" becomes "00".
    const [hexR, hexG, hexB] = channels.map(channel => {
        const hex = channel.toString(16)
        return hex.length % 2 ? "0" + hex : hex
    })

    return `#${hexR}${hexG}${hexB}`.toUpperCase()
}