Setting, reading, and deleting cookies

The following JavaScript code comes from Microsoft, specifically Technet article Q194461. This code checks for an exisiting cookie when the page is loaded, and if none exists sets a new one. If one already exists, it adds one to the value and then calls setCookie to write the new value.

<SCRIPT LANGUAGE="JavaScript">
<!--

var caution = false

// name - name of the cookie
// value - value of the cookie
// [expires] - expiration date of the cookie
// (defaults to end of current session)
// [path] - path for which the cookie is valid
// (defaults to path of calling document)
// [domain] - domain for which the cookie is valid
// (defaults to domain of calling document)
// [secure] - Boolean value indicating if
// the cookie transmission requires a secure transmission
// * an argument defaults when it is assigned null as a placeholder
// * a null placeholder is not required for trailing omitted arguments
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
}

// name - name of the cookie
// * return string containing value
// of specified cookie or null if cookie
// does not exist
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))
}

// name - name of the cookie
// [path] - path of the cookie
// (must be same as path used to create cookie)
// [domain] - domain of the cookie
// (must be same as domain used to create cookie)
// * path and domain default if assigned
// null or omitted if no explicit argument proceeds
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"
}
}

// date - any instance of the Date object
// * you should hand all instances of the
// Date object to this function for "repairs"
// * this function is taken from
// Chapter 14, "Time and Date in JavaScript", in
// "Learn Advanced JavaScript Programming"
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() + 365 * 24 * 60 * 60 * 1000)
var visits = getCookie("counter")
if (!visits)
visits = 1
else
visits = parseInt(visits) + 1
setCookie("counter", visits, now)
document.write("You have been here " + visits + " time(s).")

// -->
</SCRIPT>


Click here to increase this number.
Delete the cookie - technically, this does not actually delete the cookie, it sets the expiry date to 1/1/70. Click refresh after deleting, to see the number set back to one.