It's a simple feature that most people would overlook. They didn't specify exactly how in depth or "involved" the solution should be, or if I could just import a library that meets most of the requirements. I decided to demonstrate my depth of understanding of React projects, so instead of just importing a library and call it a day, I wrote the functionality from scratch with the help of redux, redux-saga, and some CSS library. They ended up liking my solution, though they said it's "a bit too involved" for their taste.