JSFiddle - React, Tailwind, and code Playground

HTML

<body class="full">
    <div class="fullscreen-overlay" id="fullscreen_overlay">
  <div class="fullscreen-container js-fullscreen-container">
<div class="textarea-wrap">
  <textarea name="fullscreen-contents" id="fullscreen-contents"></textarea>
</div>
 </div>
</div>
</body>

JavaScript

var text = document.getElementById('fullscreen-contents');



function saveText() {
    localStorage.savedText = text.value;
    console.log("saved");
}

function getText() {
    if (localStorage.savedText) {
        text.value = localStorage.savedText;
        console.log("loaded");
    }
}

/* normally, you would attach getText() to your onload event.
   However, jsFiddle calls onload automatically, so attaching
   this function to onload was causing me problems */

//window.onload(getText);
getText();
window.addEventListener("unload", saveText, false);