Timing of effects

Although useEffect is deferred until after the browser has painted, it's guaranteed to fire before any new renders. React will always flush a previous render's effects before starting a new update.

Is this true in both concurrent and non-concurrent mode. It would appear intuitively that these two call-sites in non-concurrent mode would be deterministic:

ReactDOM.render(<Foo>, container)
ReactDOM.render(<Foo>, container)

That is it would invoke a new render before the effect in the first render has been invoked.

If so would it make more sense to specify it is only in relation to effects i.e previous effects are guaranteed to run before future effects.

As it stands, it looks appears as though the "render" call-site is non-deterministic in non-concurrent.

Inizia esaminando l’affermazione citata nella documentazione secondo cui gli effetti vengono svuotati prima dei nuovi render, quindi confronta la sua formulazione con i due punti di chiamata di ReactDOM.render e con il comportamento sia concurrent sia non-concurrent. Il lavoro è concluso quando la documentazione dichiara chiaramente la garanzia supportata e chiarisce se si applica ai render in generale o solo all’ordine degli effetti.