JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <style type="text/css">
        div {
            width: 14px;
            height: 14px;
            border: 1px solid blue;
            background-color: red;
        }    
    </style>
    
    <script type="text/javascript">
        var s, d;
        window.onload = function() {
            s = document.querySelector('span');
            d = document.querySelector('div');
            setInterval(updateWidth, 100);
        }
        
        function updateWidth() {
            s.innerHTML = d.offsetWidth;
        }
    </script>
</head>

<body>
    <div></div>
    <p>offsetWidth of div element is: <span></span></p> 
</body>
</html>