credit-card.js

function digitalRoot (n) {
  return n === 0 ? 0 : 1 + ((n - 1) % 9)
}

function sum (a,b) { return a + b }

function luhn (x) {
  return String(x)
    .trim()
    .split("")
    .map(n => parseInt(n, 10))
    .reverse()
    .map((n,i) => i % 2 ? digitalRoot(n * 2) : n)
    .reduce(sum) % 10 === 0
}

function type (x) {
  let n = String(x).trim()
  switch (true) {
  case (/^4[0-9]{12}(?:[0-9]{3})?$/).test(n):        return "vi" // Visa
  case (/^5[1-5][0-9]{14}$/).test(n):                return "mc" // Master Card 
  case (/^3(?:0[0-5]|[68][0-9])[0-9]{11}$/).test(n): return "dc" // Diners Club
  case (/^3[47][0-9]{13}$/).test(n):                 return "ax" // American Express
  case (/^6(?:011|5[0-9]{2})[0-9]{12}$/).test(n):    return "dd" // Discover
  case (/^1[0-9]{14,15}$/).test(n):                  return "tp" // uapt
  case (/^(?:2131|1800|35\d{3})\d{11}$/).test(n):    return "jc" // japan credit bureau
  default:                                           return "unknown"
  }
}





// Tests
function pad (w, t) {
  t = String(t).trim()
  let x = 1
  while (t.length <= w) {
    t = x % 2 ? (t + " ") : (" " + t) 
    x++
  }
  return t
}

console.log(`${pad(14, "luhn")} ${pad(18,"type")} ${pad(17,"Number")}`)
console.log(`===============|===================|===================|`)
const good = 
[ ["vi", true, 4111111111111111]
, ["vi", true, 4012888888881881]
, ["ax", true, 378282246310005]
, ["dd", true, 6011111111111117]
, ["mc", true, 5105105105105100]
, ["ax", true, '378282246310005']
, ["ax", true, '371449635398431']
, ["ax", true, '378734493671000']
, ["dc", true, '30569309025904']
, ["dc", true, '38520000023237']
, ["vi", true, '4111111111111111']
, ["vi", true, '4012888888881881']
, ["vi", true, '4222222222222']
, ["mc", true, '5555555555554444']
, ["mv", true, '5105105105105100 ']
, ["dd", true, '6011111111111117']
, ["dd", true, '6011000990139424']
, ["mc", false, 5105105105105106]
, ["unknown", false, "bob"]
].forEach(n => console.log(`|${pad(6,n[1])} ${pad(5,luhn(n[2]))}|${pad(8,n[0])} ${pad(8,type(n[2]))}|${pad(18,n[2])}|`))
console.log(`===============|===================|===================|`)