title: How to store previously seen posts in infinite scroll
body: <p>I am making a website (coded in reactjs with firebase/firestore as backend) where users can go through posts with infinite scrolling (like on tumblr). However, I am confused about how I should store posts that have already been loaded. I was thinking of storing them in an array as part of my component state, but I don't know how much data it's ok to store in state - after the user has been scrolling for a while there will be a lot of loaded posts that I have to store. Is there a better/more efficient way to do this? Thanks!</p>