Format credit card

formatCreditCard.js

function formatCrediCard(cardtype, number)
{
    let format;
    if(cardtype == 'amex')
    {
        //XXXX XXXXXX XXXXX
        format = number.substr(0,4)+" "+number.substr(4,6)+" "+number.substr(10,5);
    } else {
        //XXXX XXXX XXXX XXXX
        format = number.substr(0,4)+" "+number.substr(4,4)+" "+number.substr(8,4)+" "+number.substr(12,4);
    }
    return format;
}

//Fake credit card generation https://www.fakenamegenerator.com/
//Example
console.log(formatCard('amex','347104348907272'));

console.log(formatCard('mastercard','5102186963653038'));