Datatables, as the name suggests is used to show data in tables in paginated format. It is very easy to use and customizable.
Example of Pagination using Datatables Js Library
Step by Step tutorial on how to create pagination table using datatables js library
Lazysizes is another js library each developer can learn about easily. What it does is, it makes the images on the webpage load only when they enter the screen. This way, page speed can be improved to a large extent as images are responsible for most of the page weight.
Step by Step tutorial on how to lazyload images using lazysizes js library