JSFiddle - React, Tailwind, and code Playground
JavaScript
var n = "1234567890123456";
document.write(n.replace(/(\d{4})(\d{4})(\d{4})(\d{4})/, "$1-$2-$3-$4"));
var n = "1234567890123456";
document.write(n.replace(/(\d{4})(\d{4})(\d{4})(\d{4})/, "$1-$2-$3-$4"));