JSFiddle - React, Tailwind, and code Playground

HTML

<span style="display: none;">I'm only visible after window.deferred</span>
<script>
  window.deferred = window.deferred || {};
  window.deferred.afunction = function() {
    console.log('afunction is running');
    document.getElementsByTagName('span')[0].style.display = 'block';
  };
  window.deferred.anotherfunction = function() {
    document.getElementsByTagName('span')[0].innerHTML += '...and I have extra content!';
  };
</script>

JavaScript

/* Run deferred functions */
if(window.deferred && typeof window.deferred === 'object') {
  for (var fn in window.deferred) {
    if (typeof window.deferred[fn] == 'function') {
      window.deferred[fn]();
    }
  }
}