The literary device is generally used to build anticipation in the minds of readers about what might happen next to add dramatic tension to a story.
Flashforwards move the plot forward in time where formerly revealed or new character traits, events or themes are brought into the story.
A flashforward is a scene that takes the narrative forward in time from the current point of the story in literature, film, television, or other media.
[11] Found notably in the epic novels of Leo Tolstoy and Fyodor Dostoevsky, sideshadowing is the practice of including scenes that turn out to have no relevance to the plot.
That, according to Morson, increases the verisimilitude of the fiction because the audience knows that in real life, unlike in novels, most events are in fact inconsequential.