hexToRgba.js

const verifyColor = (a, alpha) => {
    return /^((([A-Fa-f\d]){3}){1,2})$/.test(a) && Number(alpha)>= 0 && Number(alpha)<=1
}
const parseColor = (a) => {
    if (a.length === 3){
      const groups =  /^([a-f\d]{1})([a-f\d]{1})([a-f\d]{1})$/i.exec(a)
      return [parseInt(groups[1], 16)*17, parseInt(groups[2], 16)*17,parseInt(groups[3], 16)*17]
    } else if (a.length === 6) {
      const groups =  /^([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(a)
      return [parseInt(groups[1], 16), parseInt(groups[2], 16),parseInt(groups[3], 16)]
    }
}

const hexToRgba = (a, alpha) => {
  if (verifyColor(a, alpha)) {
    const result = parseColor(a)
    return `rgba(${result[0]}, ${result[1]}, ${result[2]}, ${alpha})`
  }
  throw "Unvalid Color HEX value" 
}