Why React 18 Broke Your App

You’ve just gotten done with your React 18 upgrade, and, after some light QA testing, don’t find anything. You decide to make a minimal reproduction and create a demo of said hook. You expect it to throw an “alert” dialog after a second of waiting, but weirdly, the dialog never runs at all. The reason your app broke in React 18 is that you’re using Strict Mode.