how to know if ur browser is blocking js code example

Example: check if js is enabled

<script>
    document.write("Hello JavaScript!")       
</script>
<noscript>
    <style type="text/css">
        .pagecontainer {display:none;}
    </style>
    <div class="noscriptmsg">
    You don't have javascript enabled.  Good luck with that.
    </div>
</noscript>