JS统计在线人数（包含cookie存读删）

<script language="JavaScript">
<!--
var caution = false
function setCookie(name, value, expires, path, domain, secure) {
var curCookie = name + "=" + escape(value) +
((expires) ? "; expires=" + expires.toGMTString() : "") +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
((secure) ? "; secure" : "")
if (!caution || (name + "=" + escape(value)).length <= 4000)
document.cookie = curCookie
else
if (confirm("Cookie exceeds 4KB and will be cut!"))
document.cookie = curCookie
}
function getCookie(name) {
var prefix = name + "="
var cookieStartIndex = document.cookie.indexOf(prefix)
if (cookieStartIndex == -1)
return null
var cookieEndIndex = document.cookie.indexOf(";", cookieStartIndex + prefix.length)
if (cookieEndIndex == -1)
cookieEndIndex = document.cookie.length
return unescape(document.cookie.substring(cookieStartIndex + prefix.length, cookieEndIndex))
}
function deleteCookie(name, path, domain) {
if (getCookie(name)) {
document.cookie = name + "=" +
((path) ? "; path=" + path : "") +
((domain) ? "; domain=" + domain : "") +
"; expires=Thu, 01-Jan-70 00:00:01 GMT"
}
}
function fixDate(date) {
var base = new Date(0)
var skew = base.getTime()
if (skew > 0)
date.setTime(date.getTime() - skew)
}
var now = new Date()
fixDate(now)
now.setTime(now.getTime() +  5 * 60 * 1000)
var visits = getCookie("counter")
// -->
</script>

<td>网站访问量 <span>
<script type="text/javascript">
if (!visits)
visits = $onlineNum
else
if(visits < $onlineNum)
visits = $onlineNum;
visits = parseInt(visits) + 1
setCookie("counter", visits, now)
document.write(visits)
</script>
</span> 人</td>
</tr>