flushSync is part of what I like to call “Rare React”; the curious & uncommon parts, the outer circle of the API, the rarely needed sharp knives. That just so happens to be a thing that I enjoy diving into and writing a blog post about. So what does ReactDOM.flushSync do and when is it useful? The names suggest it flushes synchronously. But what is flushing, what is being flushed, and when should