JSFiddle - React, Tailwind, and code Playground

HTML

<div id="out">

</div>

JavaScript

function getMethods(o) {
  return Object.getOwnPropertyNames(Object.getPrototypeOf(o))
    .filter(m => 'function' === typeof o[m])
}

document.getElementById('out').innerHTML += `getMethods(new Date()):<br/>${getMethods(new Date())}<br/><br/>`;
document.getElementById('out').innerHTML += `getMethods("hello"):<br/>${getMethods("hello")}<br/><br/>`;