This post is part two of a series on building a custom React video chat app using Daily's real-time video and audio APIs, and Daily's custom React hooks library. In this post, we'll be adding a prejoin UI to our application, which allows participants to preview their video before joining, select their preferred devices (camera and microphone), and set their username. We'll use the preAuth() and startCamera() daily-js methods to authenticate ourselves and see ourselves on the screen without having to join the call first. The new <HairCheck/> component will be implemented using Daily React Hooks extensively.