How do I make a web page repeat the content (a block of text) every time a user hits the end of the web page – like with infinite scroll, but with the same content?
A thread that already answers your question:
Javascript how to detect if browser window is scrolled to the bottom
And to make it infinite you simply append a tag with its content every time the "window-bottom" state is reached.
This could be expressed as such:
window.onscroll = function(ev) {
if ((window.innerHeight + window.scrollY) >= document.body.offsetHeight) {
// you're at the bottom of the page
var div = document.createElement('div')
div.innerHTML = "your content"
document.body.appendChild(div)
}
}