Geração de Payment Token e Identificação de Bandeira de Cartão

export function creditCardType(cc: string) {
let amex = new RegExp('^3[47][0-9]{13}$');
let visa = new RegExp('^4[0-9]{12}(?:[0-9]{3})?$');
let cup1 = new RegExp('^62[0-9]{14}[0-9]$');
let cup2 = new RegExp('^81[0-9]{14}[0-9]$');

let mastercard = new RegExp('^5[1-5][0-9]{14}$');
let mastercard2 = new RegExp('^2[2-7][0-9]{14}$');

let disco1 = new RegExp('^6011[0-9]{12}[0-9]$');
let disco2 = new RegExp('^62[24568][0-9]{13}[0-9]$');
let disco3 = new RegExp('^6[45][0-9]{14}[0-9]$');

let diners = new RegExp('^3[0689][0-9]{12}[0-9]$');
let jcb = new RegExp('^35[0-9]{14}[0-9]$');


if (visa.test(cc)) {
return 'VISA';
}
if (amex.test(cc)) {
return 'AMEX';
}
if (mastercard.test(cc) || mastercard2.test(cc)) {
return 'MASTERCARD';
}
if (disco1.test(cc) || disco2.test(cc) || disco3.test(cc)) {
return 'DISCOVER';
}
if (diners.test(cc)) {
return 'DINERS';
}
if (jcb.test(cc)) {
return 'JCB';
}
if (cup1.test(cc) || cup2.test(cc)) {
return 'CHINA_UNION_PAY';
}
return undefined;
}