Take it with you

Copy the check

The whole Luhn check fits in about fifteen lines. Each version below does the same thing: strip spaces and dashes, require 12 to 19 digits, then double, fold and add.

export function passesLuhn(input: string): boolean {
  const digits = input.replace(/[\s-]/g, "");
  if (!/^\d{12,19}$/.test(digits)) return false;

  let sum = 0;
  for (let i = 0; i < digits.length; i++) {
    let d = Number(digits[digits.length - 1 - i]);
    if (i % 2 === 1) {
      d *= 2;
      if (d > 9) d -= 9;
    }
    sum += d;
  }
  return sum % 10 === 0;
}

Before you ship it

Run the same check on your server. Anything a browser does can be skipped by someone who is not using your page.
Do not log card numbers, even failed ones. If you can, avoid handling them at all and use your payment provider's hosted fields.
Do not reject a number only because its brand is unknown to you. New ranges appear, so let the payment provider decide.
Accept spaces and dashes when people paste a number, and format it for them as they type.