That is pretty nifty and also pretty intricate. There are actually two JS files responsible here, one is zomer.min.js and the other one is script.min.js; and as the filenames indicate, the scripts are minified (compressed, to save file size). You can easily uncompress them with numerous online tools such as http://jsbeautifier.org/
. In zomer there are actually a few file paths, it looks like mainly for the moving people sprites.
The best would be to save the page as plain HTML. If you save it as complete website it saves it with the generated HTML (i. e. the stuff that’s generated and appended by JS) which is definitely confusing to work with. So, save page as plain HTML, save all relevant scripts and stylesheets manually (you can do “view source”, click on the script links, and then “Ctrl/Cmd+S”), and get the images by doing “Ctrl/Cmd+I” (page info), clicking the Media tab, and there you have all images that are used. There is a “save as” button, you can select multiple files and save them all.
Just keep in mind that you need to reflect the file structure of the original site.