rgba.js

const rgba = (value, opacity) => {
  const isHex = hex => {
    return /(^#[0-9A-F]{6}$)|(^#[0-9A-F]{3}$)/i.test(hex)
  }

  const hexToRGB = hex => {
    const shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i

    const longHex = hex.replace(shorthandRegex, function(m, r, g, b) {
      return r + r + g + g + b + b
    })

    let result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(longHex)

    return result
      ? `${parseInt(result[1], 16)}, ${parseInt(result[2], 16)}, ${parseInt(
          result[3],
          16
        )}`
      : null
  }

  if (isHex(value)) {
    const rgb = hexToRGB(value)

    return `rgba(${rgb}, ${opacity})`
  }

  console.log('stop sending me not hex values')
  return null
}