In web programming, it is very important to care for the lifespan of every cookie that exists in a cookie collection as users navigate through the website.
Often, cookies are used to stored vital information that are needed mostly to determine what section of the website an individual user is qualified to enjoy or not.
For instance, on a website that depends on subscription, free mode or trial mode, cookies are used to track what section of the website is to be displayed to the users.
Hence, the important of taking seriously, cookie collection management.
Consider a situation when your users shared the same device to access your website using their different login credentials.
In this scenario, if you leave your cookie unmanaged, once one of the users sharing the same device logged in with his/her PREMIUM account, every other user who use the device will inherit the PREMIUM cookie value that has been set by the only one premium user.
However, when you clear all your website cookies values on logout, each user will be welcomed to enjoy exactly what they are entitled to on your website.
There are several means of clearing cookie collection in a c# website, using both C# Programming language and JavaScript; and each with their pros and cons.
Below is a list of some means of clearing user's cookies on logout.
The above method will typically clear all the cookies attributed to a website domain at once but you should be cautious of using this method even though it is the simplest and very fast but if your website needs to preserve some cookie values, they will be cleared along.
- Setting the Expiry Date of All Existing Cookie
You can alternatively set the expiry date of all the cookies associated with a website domain by iterating through the cookies keys and setting a backdated value as their expiry day.
For example:
var cookieNames = HttpContext.Current.Request.Cookies.AllKeys.ToList();
foreach (var cookieName in cookieNames)
{
HttpContext.Current.Response.Cookies.Add(new HttpCookie(cookieName) { Expires = DateTime.Now.AddDays(-1) });
}
- Selectively Setting Expiry Date for Cookie Names
You can alternatively collate a list of important cookie names that are linked to the determination of what your users see and cannot see. Then, set their expiry date once on logout.
An example is given below:
Response.Cookies["CookieA"].Expires=Response.Cookies["CookieB"].Expires=Response.Cookies["CookieC"].Expires=Date time.Now.AddDays(-1); //-1 sets the expiry date of the cookies to yesterday, making all the collated cookies useless for subsequent users except they are eligible.
While the above codes are used to clear the cookies after server sides postback, the same can be achieved using JavaScript that run on the client side.
- Clear All Cookies Tied To A Website Using JavaScript
Below is the JavaScript to clear all cookies tied to a particular website.
function clearAllCookies() {
var cookies = document.cookie.split("; ");
for (var c = 0; c < cookies.length; c++) {
var cookieName = cookies[c].split("=")[0];
document.cookie = cookieName + "=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/";
}
}
This function works by:
1. Splitting the `document.cookie` string into an array of individual cookies.
2. Looping through each cookie and extracting its name.
3. Setting the cookie's expiration date to a date in the past (January 1, 1970), which effectively deletes the cookie.
Note that this code only clears cookies that are accessible to the current page's domain and path. If you want to clear cookies for a specific domain or path, you'll need to modify the `path` parameter accordingly.
For example, to clear cookies for a specific domain, you can use:
document.cookie = cookieName + "=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=/; domain=yourdomain.com";
Replace `yourdomain.com` with the actual domain you want to target.