The original game can be found at http://orteil.dashnet.org/cookieclicker/
This mirror for, errrr, like, educational purpose, either to download for your own offline education or to be played online from http://sremagris.github.io/cook/ if you cannot "educate" yourself on the original URL
Download the source code, and open index.html.
If the original game updates, run update.sh.
If you happen to update, please make a pull request for others to benefit, thanks!