Js hide

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>
<body>
<form action="test.html " method="post" title="Post Comment" >
    <textarea cols="41" rows="5" wrap="hard" id="comment"></textarea>
    <br />
    <br />
    <a id="CmtBox" onClick="link" href="#">Comment</a>

</form>
<script>

document.getElementById("CmtBox").onclick = function () {
    var comment = document.getElementById("comment");
    comment.className = (/\bhide\b/).test(comment.className) ? '' : 'hide';
    return false; //cancel default link action
};
</script>
</body>
</html>