Nowadays, almost every web browser supports JavaScript. If it is turned off, you can use <noscript> tag. To let users know about non-JavaScript web browsers, use the <noscript> tag. The HTML <noscript> tag is used to handle the browsers, which do recognize <script> tag but do not support scripting. This tag is used to display an alternate text message.
Example
<!DOCTYPE html>
<html>
<head>
<title>HTML noscript Tag</title>
</head>
<body>
<script type = "text/JavaScript">
<!--
document.write("Hello JavaScript!")
-->
</script>
<noscript>
Your browser does not support JavaScript!
</noscript>
</body>
</html>