Must the prefetch/render tags be present at first load, or might they be added dynamically with JavaScript? Pagination is a good example, since a news site migh

Must the prefetch/render tags be present at first load, or might they be added dynamically with JavaScript? Pagination is a good example, since a news site might want to load the second page of an article only after the user get so far in. Single-page sites are another good use case.