This is a bot, who will automaticaly check all pages of your website from your sitemap.xml with the size of viewport you want and create a screenshoot of each page to see if you have some issues to fix in one of them.
Go to pageScraper.js and change url variable to the url of your sitemap (line 2) and the size of the viewport (line 13).
To run the project, just use the command: node index.js