JSFiddle - React, Tailwind, and code Playground

HTML

<script>
    function b64_to_utf8( str ) {
        return unescape(decodeURIComponent(window.atob( str )));
    }
    // alert("Hello World"); in base64 code:
    // YWxlcnQlMjUyOCUyNTIySGVsbG8lMjUyMFdvcmxkJTI1MjIlMjUyOSUyNTNC
    
    document.write('<script>' + b64_to_utf8('YWxlcnQlMjUyOCUyNTIySGVsbG8lMjUyMFdvcmxkJTI1MjIlMjUyOSUyNTNC') + '</' + 'script>');
</script>