The following code illustrates how to grab/view the contents of the user's clipboard using a JavaScript Code.
<form name="myForm" method="POST" action="--WEBBOT-SELF--">
<textarea name="myField"></textarea>
</form>
<script language="javascript">
var content = clipboardData.getData("Text");
document.forms["myForm"].elements["myField"].value = content;
</script>