Usage (the video is hosted on youtube, vpn will be needed if you’re living in china):

SRC:
https://github.com/anakornk/PKU-ShuaKe-Chrome-Extension/
Install the extension from Chrome Webstore:
https://chrome.google.com/webstore/detail/pku-北大选课刷课助手/gobjpclkanepkinkgbmebkacaimgblfp