Format credit card number

Question

How to format and validate a credit card number with spaces between each 4 digit while typing:

eg: 4464 6846 4354 3564

I have tried:

Answer 1

function testCreditCard () {
  myCardNo = document.getElementById('CardNumber').value;
  myCardType = document.getElementById('CardType').value;
  if (checkCreditCard (myCardNo,myCardType)) {
    alert ("Credit card has a valid format")
  } 
  else {alert (ccErrors[ccErrorNo])};
}

check this link for lib http://www.braemoor.co.uk/software/creditcard.shtml