For existing one page site you have to produce preloader.
Site already made consist of 2 parts:
1. constant html
2. ajax loader on scroll event with sticky bar. Each time I scroll ajax-loader load 6 sectors with links to 6 random videos from xml base.
You have to make preloader. This mean that firstly onload event preloader apear then firt part of ajax context loaded preloader disapear. When I scroll down scroll event executed then your preloader apear and disaper after next portion of ajax content loaded. And so on.
Type of preloader is up to You - pure css, svg or any You want.
I am looking for a mix of experience and value