take the introduction of momentjs online as an example. When introduced online, the page will automatically generate cookie under the root domain name of momentjs, but when I checked the source code of momentjs, I did not find any code implanted in cookie, nor did I find any extra connections, and I found that this happens when many js plug-ins are introduced online, so I want to know how this cookie is generated and how it works

<script src="http://momentjs.com/downloads/moment.js">    </script>