JSFiddle - React, Tailwind, and code Playground

JavaScript

window.onerror = alert;

function toggleAndSave(el, state) {
  	el.style.display = state ? '' : 'none';
    localStorage.invisible = state;
}

window.addEventListener('load', function() {
	var checkbox    = document.createElement('input'),
  		modal       = document.createElement('span'),
      wrap        = document.createDocumentFragment();
  checkbox.type   = 'checkbox';
  checkbox.addEventListener('click', function() {
  	toggleAndSave(modal, this.checked);
  })
  modal.innerHTML = 'SCRIPTED';
  wrap.appendChild(checkbox);
  wrap.appendChild(modal);
	if(localStorage.invisible === 'true') {
  	checkbox.checked = true;
  	toggleAndSave(modal, true);
  }
  document.body.appendChild(wrap);
});