JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.14.0/ramda.min.js"></script>

JavaScript

var cardNumber       = '4761640026883566';
console.log(maskCard(cardNumber));

function maskCard(num) {
  return `${'*'.repeat(num.length - 4)}${num.substr(num.length - 4)}`;
}