Disclaimer Page Cookies

I found a disclaimer script from the web and installed on my site, I am newbie to javascipt, and hope someone could help.

How can I modify the script so that every time a user close the browser windows and visit the site, they need to accept the disclaimer again??

Thanks a lot for your suggestion in advance.

<script type='text/javascript' >
// Disclaimer DHTML
// Copyright Outils.XXX 2012

function ScanCookie(variable)
  if(place<=-1) return("0");
  if(end<=-1) return(unescape(cook.substring(place+variable.length,cook.length)));
  else return(unescape(cook.substring(place+variable.length,end)));

function Entrer()
 if(document.getElementById) document.getElementById("disclaimer").style.display='none'

 +"<style type=\\"text/css\\">"
 +"object{ visibility:hidden; }"
 +"#disclaimer{ text-align:left; }"
 +"#disclaimer-fond{ position:absolute; z-index:15000; width:100%; height:2000px; background:#fff; text-align:center; line-height:normal; clear:both; filter:alpha(opacity=95); -moz-opacity:0.95; opacity:0.95; }"
 +"#disclaimer-conteneur{ position:absolute; z-index:15001; width:100%; text-align:center; clear:both; }"
 +"#disclaimer-cadre{ width:718px; padding:10px; margin:150px auto 0 auto; text-align:left; background:#fff; border:#ddd 1px solid; }"
 +"#disclaimer-cadre b{ display:block; padding:10px 0 10px 0; text-align:center; font-size:21px; color:#666666; }"
 +"#disclaimer-cadre font{ display:block; padding:10px 0 20px 0; text-align:center; font-size:21px; color:#666666; }"
 +"#disclaimer-cadre p{ margin:0; padding:10px; font-size:16px; color:#666666; }"
 +"#disclaimer-cadre .boutons{ margin:0; padding:10px; text-align:center; }"
 +"#disclaimer-cadre a{ text-decoration:none; font-size:36px; font-weight:bold; color:#6D28AA; }"
 +"#disclaimer-cadre a:hover{ text-decoration:underline; }"
 +"<div id='disclaimer'><div id='disclaimer-fond'></div><div id='disclaimer-conteneur'>"
 +"<div id='disclaimer-cadre'>"
 +"<b>Site Disclaimer</b>"
 +"<p>Message here</p>"
 +"<div class='boutons'><a href='#' onclick='Entrer(); return(false)'>Accept</a> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <a rel='nofollow' href='http://www.google.com/'>Leave</a></div>"

Normally if a cookie is set without an expires time/date, the cookie will expire at the end of the session. That is, when the user closes their browser windows.

I don’t see an expires time being used with your script, so it seems at first glance as if things are already working the way that you want them to be.
However, since you are posting this, something clearly isn’t going according to plan.

Does it not show again when the web browser is closed and then opened again?