ITP Cookie Saver — Convert javascript cookies to server cookies

Description

This plugin removes the seven days limitations of cookies in certain browsers. Many browsers start to limit the cookie lifetime of cookies which are set by javascript to a short period of time, e.g. Safaris ITP 2.1.

Why is the limitation of the lifetime a Problem?

Depending on your website their might be a lot of Problems. The two main challenges might be:
1. Tracking
2. Cookie Consent Banner

Tracking
Most Tracking Tools, like Google Analytics for example are setting their cookies by javascript. If the cookie is deleted after seven days, the tools are not able to recognize the user as a returning user anymore, so after seven days of absence every user is a new user.

Cookie Consent Banner
It is a problem, if the cookie consent banner implementation sets the cookie with javascript. This is how most of the banner implementation do it.
If the cookie lifetime is limited by the browser to seven days, the user will see the banner every seven days, even if he made already a choice.
This can be annoying and conversion relevant.

How does this Plugin work exactly?

As part of the HTTP protocol all cookies are always send to the backend with every request.
This plugin uses this fact, by checking every request if one of the defined cookies is present. If a defined cookie is present, it sets it with the same value again.

Now the cookie is set by the server and the javascript cookie lifetime limitation is bypassed.

A challenge with this approach might be, that the cookie is set at the beginning of a page load. During page load there might be javascripts, which overwrite the cookie. In that case the javascript cookie lifetime limitation is kicking in again.

This can be avoided by checking the «before unload»- feature. With this feature enabled, everytime the user leaves a page, an additional request is send in the background and the cookies are set again.
So you can be sure, the server was the last to touch the cookie.