Check if user has clicked on submit button based on client/server side

[cle tan]

 if(process1Submit==null){ %>
				  <script type="text/javascript">
				  alert('You have not entered the details and clicked the submit button, redirecting to the previous page.');
	document.location.href='previous.jsp';
  </script>
		<% if(no javascript){

 throw new Exception('You have not entered the details and clicked the submit button, redirecting to the previous page.');	}}

process1Submit is set when the submit button is clicked on the previous page, I want the user to redirect to the previous page to press submit and not just go to the next page by changing url without pressing submit button

And I wish to check using client and server side, is there anyway to check whether javascript is enabled in the browser
This is because if i just put throw new Exception, when javascript is enabled, it will throw the error in the error page.