<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>runme</title>
</head>
<body>
<h1 id="changeme">If you see this then JavaScript did not run.</h1>
<script>
document.querySelector('#changeme').innerHTML = "If you see this, then JavaScript ran.";
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>runme</title>
</head>
<body>
<h1 id="changeme">If you see this then jQuery did not run.</h1>
<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<script>
//document.querySelector('#changeme').innerHTML = "If you see this, then JavaScript ran.");
$('#changeme').html("If you see this, then jQuery ran.");
</script>
</body>
</html>